Method of forming thin film patterning substrate including formation of banks

ABSTRACT

Display devices such as EL elements or LED elements, are formed from thin film elements having banks of prescribed height and a thin film layer formed by an ink jet method in areas to be coated that are partitioned by those banks. The banks may be formed of an organic material on a bank formation surface configured of an inorganic material, plasma treatment is performed under conditions that the induction gas is fluorine-based and that fluorine is present excessively, and the areas enclosed by the banks subjected to surface treatment are filled with the liquid thin film material to form the thin film layer or layers.

TECHNICAL FIELD

This invention relates to thin film formation technology suitable formanufacturing color filters or display elements such as LEDs (lightemitting diodes) or EL (electro-luminescence) devices which use organicsemiconductor films.

More particularly, the present invention relates to substrates, a thinfilm formation method, and thin film elements used in forming patternson substrates when thin films having different properties are formed onthe same substrate. The present invention also relates to a method offorming thin films on which fine patterning is required, wherewith it isboth easy to form thin film layers using an ink jet process and possibleto form flat thin film layers. The present invention further relates toa surface modification method for performing superfine patterningwherewith a liquid thin film material is deployed in areas enclosed inbanks formed on a substrate, using an ink jet method or spin coating,etc., as well as to a method that employs this surface modificationmethod in forming thin films and to both a display element comprisingsuch a thin film and a manufacturing method therefor.

BACKGROUND ART

In recent years, technology has been under development for obtainingfunctional devices by forming prescribed patterns by applying thin filmshaving differing properties on the same substrate. One promising methodtherefor uses an ink jet process in forming patterns with different thinfilm patterns on the same substrate. When an ink jet process is used,however, a problem arises at the process surface in that the differentthin film materials become mixed on the substrate. In more specificterms, the technology used employs an ink jet process in applying anorganic semiconductor material in producing EL devices or other displayelements, or a colored resin or other thin film material in producingcolor filters, but, when the ink jet process is used to deploy a liquidmaterial when forming a thin film pattern, the liquid material that isdischarged flows over into adjacent pixels. This presents a problem.

What is commonly done to overcome problems such as this is to provideprotruding partitioning members (called “banks” or “risers”) topartition off different thin film areas, and then to fill the areasenclosed by these partitioning members with the liquid materialsconstituting the different thin films. In the display element examplenoted above, a method is adopted wherein partitioning members areprovided to partition off the various pigment areas, and filling theareas enclosed by the partitioning areas with the materials thatconfigure the pixels.

In recent functional devices, and particularly in display elements,thinness is generally demanded, and, despite the fact that this placeslimitations on the height of the partitioning members, the volume ofliquid material deployed in the areas enclosed by the partitioningmembers is far greater than the volume remaining after film fabrication.

For this reason, problems arise in terms of poor balance between thesize of the liquid droplets discharged into the areas enclosed by thepartitioning members and the surface areas both of the partitioningmember surfaces and of the areas enclosed therein. This problem will nowbe described further.

In cases where the partitioning members exhibit liquid affinity orwettability relative to the liquid material that is the thin filmmaterial to be deployed, the desired film thickness cannot be obtainedin the final thin film even when partitioning members are present since[the liquid material] is pulled by the partitioning members. If thevolume of liquid material is made greater, moreover, the liquid materialreadily flows out into the adjacent areas.

Nevertheless, the surfaces of the areas enclosed by the partitioningmembers need to exhibit strong liquid affinity and wettability relativeto the liquid material so that the liquid material will uniformly wetand spread over those surfaces. If that is not the case, the liquidmaterial will not wet and spread over the areas enclosed by thepartitioning members, and, with display elements such as EL devices, inparticular, color loss and color irregularity will develop in thepixels.

To deal with problems such as these, technology is proposed in JapanesePatent Laid-Open No. 09-203803 and Japanese Patent Laid-Open No.09-230129, as published, for example, wherein surface treatments areemployed to make the upper portions of the partitioning membersliquid-repellant and to make the other portions exhibit liquid affinity.

In all of these examples of the prior art, a layer composed of aliquid-repellant material (a layer made of a fluorine compound) isformed on the upper surface of the partitioning members. In JapanesePatent Laid-Open No.09-203803, as published, technology is cited whereina layer exhibiting non-affinity is coated onto the upper portions of thepartitioning members, and the surfaces of the areas enclosed by thepartitioning members are treated with a hydrophilic base-surface-activeagent. In Japanese Patent Laid-Open No.09-230129, as published,technology is cited for giving the recessed portions enclosed by thepartitioning members affinity by additionally exposing them to UVradiation. The theoretical background for this is set forth in“International Display Research Conference 1997,” pp 238-241.

However, even when water repellency in the upper surfaces of thepartitioning members and liquid affinity in the areas enclosed by thepartitioning members are to some degree realized, in cases where theliquid material is applied using an ink jet process, for example, if thesize of the liquid droplets discharged is extremely large or smallrelative to the surface area of the surfaces of the partitioning membersnoted above or of the areas enclosed thereby, or if the balancetherebetween is otherwise very poor, it is known that the liquidmaterial is not accurately deployed in the areas coated, so thathigh-precision patterning becomes impossible. When, for example, thesize of the liquid droplets noted above is larger than the areasenclosed by the partitioning members to too great an extent, the liquiddroplets cross over the partitioning members, and, when the uppersurfaces of the partitioning members are narrow, the liquid dropletsspill over into areas adjacent to the areas being coated.

In cases such as this, when there is an unsuitable relationship betweenliquid droplet size and the surface area of the areas enclosed by thepartitioning members, what happens is that, due to the problems notedearlier, liquid thin film materials become mixed together in the areasenclosed by the partitioning members, and film thickness variationdevelops in each thin film that is formed.

Problems also arise which relate to the affinity of the partitioningmembers toward the liquid thin film material when that thin filmmaterial is deployed in the areas demarcated by the partitioningmembers.

The behavior of the liquid thin film material deployed differs accordingas to what sort of wettability (affinity) toward the liquid thin filmmaterial is exhibited by the partitioning members or the areas enclosedby the partitioning members. As noted earlier, when the surfaces of thepartitioning members exhibit affinity (hydrophilic property) toward theliquid thin film material, and the volume of the material deployedexceeds the height of the partitioning members, that liquid thin filmmaterial will readily flow over into neighboring areas enclosed bypartitioning members even when such partitioning members exist.Conversely, when the surfaces of the partitioning members exhibit aproper degree of non-affinity (water repellency) toward the liquid thinfilm material, that liquid thin film material will not flow over intothe neighboring areas enclosed by partitioning members even when thevolume of material deployed exceeds the height of the partitioningmembers, due to the surface tension of the material.

There are also more specific substrate surface modification methods,such as, for example, those described in the previously cited JapanesePatent Laid-Open No.09-203803 and Japanese Patent Laid-OpenNo.09-230129, as published, and also in Japanese Patent Laid-Open No.09-230127, as published. That is, specifically, technology involving amethod for subjecting bank surfaces to an ink-repellency treatment witha fluorine compound (Japanese Patent Laid-Open No.09-203803, aspublished), an etching treatment method (Japanese Patent Laid-OpenNo.09-230127, as published), and ink-affinity treatment using energyirradiation (Japanese Patent Laid-Open No.09-230129, as disclosed).

Nevertheless, when member surfaces are made ink-repellent using afluorine compound or members are formed using a fluorine compoundmaterial, in particular, the bonding strength between the fluorine-basedmaterial and the underlying layer or underlying substrate forming themembers becomes poor, which presents problems in terms of applicationsto bank-forming technology. Even if the members, and particularly thebanks themselves, are formed with an ink-repellent fluorine compoundmaterial or the like, residue develops in the bank areas afterpatterning by photolithography, whereupon there is a danger of the inkaffinity of the bank surfaces being impaired.

In the prior art described in the foregoing, moreover, the application,drying, and removal of materials exhibiting non-affinity are necessaryjust to impart non-affinity to the upper portions of the partitioningmembers, whereupon the number of process steps inevitably becomes large.Also, when UV irradiation is performed, there is a tendency for affinitywith many materials to develop. There has been a tendency for a slightaffinity to develop due to UV irradiation, even when the material is oneexhibiting non-affinity, thereby negating the effectiveness of thenon-affinity treatment. In Japanese Patent Laid-Open No. 09-230129, aspublished, in particular, there is a provision to the effect that thedegree of affinity be controlled by subjecting both the front and backsides to UV radiation, but, in terms of controlling the affinity betweennon-affinity and affinity, it is not specified how the various angles ofcontact relative to the liquid thin film material should be established.

When the liquid repellency of the partitioning members is strong,moreover, the liquid of the thin film material is repelled by the sidewalls of the partitioning members, wherefore the thickness after filmformation becomes thick in the center portions of the areas enclosed bythe partitioning members and thin about the peripheries thereof. Thisresults in color irregularities in the pixels in the display elements.In EL devices, in particular, shorts readily develop, leading to reducedreliability.

When the surfaces of the partitioning members are subjected to aliquid-repellency treatment and affinity (liquid-affinity) is impartedto the side surfaces thereof, a thin film material is provided wherewiththe thickness after film formation does not become thin about theperipheries of the areas enclosed by the partitioning members.Nevertheless, because most of the liquid of the thin film material ispulled to the side surfaces of the partitioning members, not only doesthe film thickness become greater in the lower skirt portion of the thinfilm, that is, in the portions in contact with the substrate, butneither is it difficult to control the film thickness.

There are known methods of modifying the surface energy (wettability) ofan organic substance which involve performing a plasma process. Oneexample of such a surface modification method is that described inJapanese Patent Laid-Open No. 63-308920/1988, as published. In thesurface modification method set forth in this publication, the organicsubstance surface is treated with a mixed gas plasma containing afluorine-based gas and gaseous oxygen, and the surface energy of theorganic substance is controlled by varying the mixture ratios betweenthe mixture gasses.

Methods involving UV irradiation or oxygen plasma treatment are alsowell known as procedures for making the surfaces of organic substancessuch as glass or indium tin oxide (ITO) hydrophilic.

No technology has been reported, however, for simply and rigorouslycontrolling the wettability of each material in the substrate by plasmatreatment or UV irradiation in cases where a pattern of layersconstituted by organic or inorganic substances is formed on the samesubstrate. With methods wherein ink repellency is imparted bymixture-gas plasma treatment to an organic substance surface or thesurface of a member formed of an organic substance, problems arise, suchas being unable to impart ink repellency efficiently, or that the inkrepellency of the surface is transient, or having to use a heattreatment, so that the ink repellency deteriorates with the passage oftime.

In cases where an ink-affinity treatment is performed using energyirradiation, there is a danger of impairing the ink repellency of thebank surfaces, and it is very difficult to simultaneously achieve bothbank surface ink repellency and bank surface ink affinity.

In methods for forming thin films in prescribed patterns where differentthin film materials are provided, and particularly in methods forforming thin films wherein liquid thin film materials are deployed inareas enclosed by partitioning members (banks) formed on a substrate,the proper-control of wettability (ink repellency and ink affinity) inthe banks and depressions is critical. If the banks do not exhibit inkrepellency, not only will ink residue develop on the banks, but, incases where different liquid thin film materials are deployed inadjacent depressions divided by a bank, those different liquid thin filmmaterials will overflow the bank and be mixed together. When thishappens, it is not possible to form thin films having the desiredcharacteristics.

Examples of the formation of thin films using different liquid thin filmmaterials in adjacent depressions divided by banks include color organicEL devices and color filters used in liquid crystal display elements,etc. When these devices are manufactured, however, the banks mustexhibit ink repellency and the areas enclosed by the banks, that is, thesurfaces of the ITO or glass substrate, must exhibit ink affinity. Ifthe depressions do not exhibit ink affinity, the wetting and spreadingwithin the pixels will be poor, causing color loss and film thicknessirregularity.

With the methods described in the foregoing, moreover, in addition tothe ink-repellency treatment, an ink-affinity treatment process is alsonecessary in the pixel areas, that is, in the depressions. Thus thesemethods involve difficulties in that controlling the ink supplied isdifficult and in that the number of process steps becomes large.

DISCLOSURE OF THE INVENTION

It is in the face of these circumstances that the present invention wasarrived at. The primary objects of the present invention are, whenforming film patterns using thin films of different properties on thesame substrate, to prevent liquid thin film materials from flowing overthe banks, to be able to form thin film layers that are flat and ofuniform thickness with no color irregularities, without fail, with highprecision, relatively simply, and with good yield, and to make possiblevery fine and highly detailed patterning.

A first object of the present invention is to provide thin film elementssuch as organic EL devices and color filters that—when thin films of anorganic semiconductor material or colored resin, etc., are formed by adischarge method such as ink jetting or bubble jetting—are patterned tohigh precision without the occurrence of mixing in any of the thin filmareas, and with remarkably little variation in film thickness. Anotherobject of the present invention incidental to the first object is toprovide the thin film patterning substrates to be used whenmanufacturing these thin film elements, display elements comprising suchthin film elements, and thin film formation methods for obtaining thesethin film elements.

A second object of the present invention is to provide substrate thinfilm elements and thin film formation methods wherewith even finerpatterning is possible when forming interconnections or otherelectrically conducting thin films for semiconductor devices, electronicdevices, and the like, by a spin-coating or dip method, together withthin film elements formed by such methods, display elements comprisingthese thin film elements, and electronic equipment comprising thesedisplay elements, respectively.

A third object of the present invention is to provide a method formodifying the surface of a substrate whereon are formed banks for thepurpose of conveniently and suitably controlling wettability, togetherwith methods for forming thin films using that surface modificationmethod, display elements and display devices comprising these thinfilms, and manufacturing methods therefor.

A fourth object of the present invention is to provide a thin filmformation method wherewith, by managing a plasma process under certainconditions, the affinity between banks and bank formation surfaces canbe definitely controlled while the banks themselves maintain highbonding strength with the bank formation surfaces, without requiringnumerous process steps for affinity control. Thus the liquid thin filmmaterial is prevented from flowing over the banks, yield is improved,and manufacturing costs are reduced.

A fifth object of the present invention is to provide display deviceswherewith the liquid thin film material is prevented from flowing overthe banks by definitely establishing the affinity between the banks andthe bank formation surfaces by managing a plasma process under certainconditions, which display devices have thin film layers of uniformthickness. Thus image display can be effected wherein no irregularitiesin brightness or color appear, and wherewith reliability is enhanced.

As a result of conducting assiduous research for the purpose ofachieving the first object noted above, the inventors discovered thatthe first object of the present invention can be achieved, in formingthin films using the discharge methods described earlier, by not onlyadjusting the liquid repellency of the partitioning member surfacesnoted above for a liquid material and the liquid affinity of the areasenclosed by the partitioning members, but also optimizing therelationship between the size of the liquid droplets of the liquidmaterial discharged and the surface areas of the partitioning membersand the areas enclosed by those partitioning members.

[The inventors] also discovered that, when forming thin films byspin-coating or dipping, in addition to controlling the liquid-materialwettability of the partitioning members and the areas enclosed by thepartitioning members, by adjusting the surface tension of this liquidmaterial to a certain value, the second object of the present invention,stated above, can be achieved. The present invention was perfected onthe basis of such discoveries as these.

Specifically, in order to achieve the first object noted earlier, thepresent invention is either a thin film patterning substrate comprisinga thin film layer pattern formed by an ink jet method on banks of aprescribed height and in areas to be coated which are demarcated bythose banks, or a display element formed on that patterning substrate,characterized by the fact that, when the width of the banks is made a(μm), the height thereof is made c (μm), the width of the areas to becoated is made b (μm), and the diameter of the liquid droplets of theliquid material or materials forming the thin film layer or layers ismade d (μm), the banks exhibit the following characteristics.

(1) The banks are formed on the substrate so as to satisfy therelationship d/2<b<5d. By satisfying this characteristic range, theliquid material will not ride up on the banks, and color mixing insidethe pixels is prevented. In addition, this characteristic is augmentedby at least one of the following characteristics.

(2) a>d/4: When b is small, if a>d/4, then the liquid material may rideup on the banks, but mixture of thin film materials inside the areas tobe coated is prevented.

(3) c>t₀ (where t₀ is the film thickness of the thin film layer (in μm))

-   -   (4) c>d/2b

In cases where the areas to be coated are stripes or square in shape,the parameters a and c noted above will be constant, but when the pixelsare circular, parameter a becomes the shortest distance between pixels,and parameter c becomes the diameter.

The present invention for achieving the second object noted earlier is athin film element formed so that it has banks of a specific heightformed on the substrate, areas to be coated demarcated by those banks,and thin film layers formed by a dipping or spin-coating method in thoseareas, characterized by the fact that the thin film layers are formedusing a substrate subjected to prescribed surface treatment ([for]wettability control), and using liquid material having a surface tensionof 30 dyne/cm or less.

By keeping the surface tension of the liquid synthetic resin within thisrange, it is possible to form patterned thin films of a width of a fewmicrons or less, using a spin-coating or dip method.

The present invention provides thin film formation methods for obtainingthese thin film elements, display devices comprising these thin filmelements as the display elements, and, furthermore, electronic equipmentcomprising these display devices.

The invention concept common to the inventions described below anddevised by the inventors for achieving the third and following objectsnoted earlier is a surface modification method for filling areasenclosed by banks on a substrate with a thin film forming material. [Thethird and following objects are further achieved by] surfacemodification technology having processes for uniformly subjecting theentire surface of the substrate on which the banks are formed to aseries of surface modification treatments, and, by means of that seriesof treatments, to raise the non-affinity of the bank portion surfaces tothe thin film formation material relative to that of the surface of theportions between banks, or by thin film formation technology whereinthat surface modification technology is employed, or a thin filmpatterning substrate wherein that is used, or a display element such asan EL device wherein that is used, or a display apparatus wherein thatelement is used.

Whereas with the examples of the prior art described earlier, patterningis done after subjecting the entire surface of a photoresist prior topatterning to a water repellency treatment to yield a surface-treatedbank pattern, or a surface treatment is performed wherewith masking isdone after forming the banks, as based on the present invention, aseries of treatments is performed indiscriminately on almost the entiresurface of a substrate on which banks have been preformed, whereupon thesurface treatments sought can be performed all at once, so that noprocess of a different type than the surface treatment is involvedduring the course of plasma treatment or other surface treatment. Whatis here called a series of surface modification treatments refers to aprocess, described below, for, most suitably, applying plasmatreatments, described below, all at one time to a substrate whereinbanks made of an organic material are formed on bank forming surfacesconfigured by an inorganic material.

Thereupon, the invention for achieving the third object noted earlier isa surface modification method for filling areas enclosed by banks on asubstrate with a thin film forming material, comprising: a bankformation process for forming banks with an inorganic material on bankformation surfaces configured by an inorganic material; and a surfacetreatment process for subjecting the banks and the bank formationsurfaces to surface treatment, in cases where prescribed surfacetreatment has been performed, under certain conditions such that thedegree of non-affinity exhibited by the banks for the liquid thin filmmaterial becomes higher than that of the bank formation surfaces.

Another aspect of this invention is a thin film formation method forfilling the areas enclosed by the banks with a thin film formingmaterial and forming a thin film layer or layers, comprising: a bankformation process for forming banks with an inorganic material on bankformation surfaces configured by an inorganic material; a surfacetreatment process for subjecting the banks and the bank formationsurfaces to surface treatment, in cases where prescribed surfacetreatment has been performed, under certain conditions such that thedegree of non-affinity exhibited by the banks for the liquid thin filmmaterial becomes higher than that of the bank formation surfaces; and athin film layer formation process for filling the areas enclosed by thebanks subjected to surface treatment with the liquid thin film materialand forming a thin film layer or layers.

What is meant by bank here, as described earlier, is a partitioningmember provided for partitioning pixels in a display device whereinorganic semiconductor thin film elements are used, for example, or forpartitioning pixel areas in a color filter, etc. By bank formationsurface is meant a surface on which banks are made, which may be a drivesubstrate for a display device, etc., or a transparent substrate or thelike for a color filter, etc.

For the surface treatment, a reduced-pressure plasma treatment oratmospheric-pressure plasma treatment is performed wherein plasmairradiation is conducted in a reduced-pressure atmosphere oratmospheric-pressure atmosphere, respectively, using an induction gascontaining fluorine or a fluorine compound, for example. The certainconditions refer, for example, to the performance of the plasmatreatment in a gas containing a fluorine-based compound and oxygen.Under these conditions, unreacted groups are generated by plasmadischarge on the surface of the inorganic material, those unreactedgroups are oxidized by the oxygen, and polar groups such as carbonyl orhydroxide groups are generated. Polar groups exhibit affinity towardfluids which contain polar molecules such as water, but exhibitnon-affinity toward fluids which contain nonpolar molecules. On theorganic material surface also, in parallel with the reaction describedabove, a phenomenon occurs whereby fluorine-based compound moleculesinvade the organic material surface. In particular, when there is moreof the fluorine-based compound than there is of oxygen, and the quantityof the fluorine-based compound is set at 60% or more relative to thetotal quantity of the fluorine-based compound and the oxygen, the effectof the fluorine-based compound mixing in becomes dominant over theoxidation reaction with the oxygen in a gas atmosphere wherein thequantity of the fluorine-based compound has become excessive, whereforethe surface is rendered nonpolar due to that mixing phenomenon which isstronger than the influence of the oxidation reaction. Accordingly, whenthe organic material is plasma-treated under conditions of excessivefluorine-based compound, non-affinity toward fluids containing polarmolecules will be exhibited, while affinity will be exhibited towardfluids containing nonpolar molecules.

The gases used for the gas containing fluorine or a fluorine-basedcompound include, for example, CF₄, SF₆, and CHF₃, etc. When the surfacetreatment is performed under these conditions, the surface affinitythereof is adjusted so that the angle of contact with the fluid betweenthe organic material and inorganic material becomes greatly divergent.The surface treatment conditions are set by the surface treatmentdescribed above so that the angle of contact with the bank formationsurface of the liquid thin film material becomes 20 degrees or less. Thesurface treatment conditions are also set so that the angle of contactwith the bank formation surface of the liquid thin film material becomes50 degrees or greater. When the banks are formed in two layers, theaffinity of the lower bank layer for the liquid thin film material isset, by a surface treatment, so that it is equal to or lower than thatof the pixel electrodes but equal to or greater than that of the upperbank layer. The surface treatment conditions are set, for example, sothat the surface of the upper bank layer subtends an angle of contactwith the liquid thin film material of 50 degrees or less. And thesurface treatment conditions are set so that the angle of contactsubtended by the lower bank layer with the liquid thin film material iswithin a range of 20 to 40 degrees.

Whether affinity or non-affinity is exhibited here is determined by theproperties of the liquid thin film material that is deployed. If theliquid thin film material is hydrophilic, for example, the surfaceshaving polar groups will exhibit affinity, while the surfaces havingnonpolar groups will exhibit non-affinity. Conversely, if the liquidthin film material exhibits oil-affinity, the surfaces having polargroups will exhibit non-affinity, and the surfaces having nonpolargroups will exhibit affinity. The thin film materials used will varywidely according to the manufacturing objective.

It is preferable that the bank formation process form two layers ofbanks, namely an upper layer and a lower layer. In one specific example,this bank formation process comprises a lower film layer formationprocess for forming a lower film layer on the bank formation surfaces,an upper layer formation process for forming an upper layer inconformity with the bank formation areas on the lower film layer, and aremoval process that uses the upper layer as a mask and removes, byetching, the lower film layer in the areas where that upper layer is notprovided.

In another specific example, the bank formation process comprises alower film layer formation process for forming a lower film layer on thebank formation surfaces, a process for exposing and developing thatlower film layer in conformity with the lower bank layer formationareas, an upper film layer formation process for forming an upper filmlayer covering the lower layer, and a process for exposing anddeveloping that upper film layer in conformity with the upper bank layerformation areas.

In one example application, pixel electrodes are provided in areasenclosed by banks, and the liquid thin film material is an organicsemiconductor material for forming thin film light emitting elements.This is an organic semiconductor display device. The pixel electrodeshere may be, for example; ITO electrode films. In specific terms, it isdesirable that the banks be made of an insulating organic material suchas a polyimide. In cases where a lower bank layer is provided, moreover,silicon oxide film, silicon nitride film, or amorphous silicon is used.

The present invention for achieving the fourth object noted earlier is asurface modification method for filling areas enclosed by banks formedon a substrate with a liquid thin film material. This invention providesa surface modification method which comprises a first process forperforming an oxygen plasma treatment on the substrate whereon the banksare formed, and a second process for performing, consecutively, afluorine-based gas plasma treatment.

By using this method, the surface of the glass, ITO, or other inorganicsubstrate can be made to exhibit liquid-affinity (affinity) for theliquid thin film material noted above.

The oxygen plasma treatment performed in the first process noted abovenot only ashes the residue in cases where banks are formed of organicsubstances on the substrate, but also activates the surface of theorganic substance. This is effective in performing liquid-repellencytreatment more efficiently in the fluorine-based gas plasma treatmentperformed immediately thereafter.

In the second process noted above, fluorine-based gas plasma treatmentis performed whereby the surface of the organic substance is fluoridized(Teflon-treated), making it possible to impart semi-permanent liquidrepellency to the organic substance. With this fluorine-based gas plasmatreatment, the liquid affinity exhibited on the substrate is notimpaired, and surfaces exhibiting liquid affinity and liquid repellencycan be selectively formed on the substrate by a simple method.

Furthermore, at least one of the plasma treatments of the first andsecond processes described in the foregoing may employ anatmospheric-pressure plasma in a treatment performed under atmosphericpressure. Alternatively, at least one of the plasma treatments of thefirst and second processes described in the foregoing may employ areduced-pressure plasma in a process performed under reduced pressure.

If the degree of contamination on the substrate is low, moreover, it ispermissible to perform only the fluorine-based plasma treatment. Inparticular, with a reduced-pressure plasma, the substrate surface can becleaned, and the organic substance forming the banks can beTeflon-treated.

The substrate mentioned in the foregoing can be configured from aninorganic substance. A substrate surface made of such an inorganicsubstance can also be made to exhibit liquid affinity.

It is possible to form at least the upper surfaces of the banks formedon the substrate noted above from an organic substance. Alternatively,both the upper surfaces and side surfaces of the banks formed on thesubstrate can be formed of an organic substance. It is furtherpermissible to form the banks formed on the substrate in two layerswhereof the lower layer is formed of an inorganic substance and theupper layer is formed of an organic substance. Alternatively, the banksformed on the substrate can be formed in two layers, whereof the lowerlayer is formed of an inorganic substance and the upper layer is formedof an organic substance, such that at least the side surfaces of theinorganic substance are not covered by the organic substance.

The surfaces of the organic substance forming the banks may also be madeto exhibit liquid repellency (non-affinity). Or the surfaces of theorganic substance forming the banks may be Teflon-treated.Alternatively, the surface of the organic substance forming the bankscan be made to exhibit liquid repellency and the surface of thesubstrate formed of one of the inorganic materials noted earlier can bemade to exhibit liquid affinity.

Because it is not necessary to use a material that already exhibitsliquid affinity for the organic material forming the banks, the range ofmaterials that may be selected is broadened.

Also, surface energy (liquid affinity, liquid repellency) can easily becontrolled by such conditions as process time, gas type, gas flowvolume, plasma intensity, and the distance from the plasma electrode tothe substrate, etc.

The angle of contact subtended by the liquid thin film material noted inthe foregoing with the surface of the substrate noted in the foregoingcan be made 30 degrees or less, and the angle of contact subtended withthe bank surfaces noted above can be made 50 degrees or more.

When the angle of contact subtended by the liquid thin film materialwith the substrate surface exceeds 30 degrees, the liquid thin filmmaterial will not wet and spread over the entire surface of thesubstrate enclosed by the banks or it will not uniformly wet and spread,so that film thickness irregularities will develop. When, on the otherhand, the angle of contact subtended by the liquid thin film materialwith the bank surfaces is less than 50 degrees, the liquid thin filmmaterial adheres to the upper portions of the banks, or is pulled to thebank sides and exceeds the banks, thus flowing into the adjacentsubstrates. In other words, it becomes impossible to effect patterns ofthe liquid thin film material at the desired locations.

Furthermore, by forming the banks in two layers, using an inorganicmaterial for the lower layer, and effecting control so that the angle ofcontact is from 20 to 50 degrees, the problem of the film not adheringto or becoming thin at the skirts of the banks can be resolved.

Accordingly, it becomes possible to employ an ink jet method orspin-coating method to effect liquid thin film material patterning withhigh precision in areas enclosed by banks using the surface modificationmethod described in the foregoing. If a substrate subjected to surfacemodification as described above and a thin film formation method basedon the ink jet method is employed, it becomes possible to manufacturevery fine color filters and full color EL devices simply and at lowcost.

The present invention for achieving the fifth object, furthermore, is amethod for forming thin films wherewith areas enclosed by banks formedon a substrate are filled with a liquid thin film material. Thisinvention provides a thin film formation method which comprises aprocess for filling areas enclosed by banks on a substrate subjected tothe surface modification described in the foregoing with the liquid thinfilm material noted earlier, by an ink jet method, immediately after thesurface modification.

The present invention, furthermore, for achieving the fifth objective,is a method for forming thin films by filling areas enclosed by banksformed on a substrate with a liquid thin film material, providing a thinfilm formation method that comprises a process for filling the areasenclosed by the banks on the substrate subjected to the surfacemodification described in the foregoing with the liquid thin filmmaterial noted above, by a spin-coating or dipping method, immediatelyafter that surface modification.

The present invention, furthermore, for achieving the fifth object,provides display devices which comprise thin films formed by the thinfilm formation method described above. These display devices can beconstituted of color filters or organic EL elements or the like.

The present invention, moreover, in order to achieve the fifth object,provides methods for manufacturing display devices wherein thin filmsare formed by the thin film formation methods described in theforegoing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified explanatory diagram of the relationship betweenliquid droplets and a display device of the present invention;

FIG. 2A-2C are cross-sections of example shapes for banks having liquiddroplet reservoirs in a display device of the present invention;

FIG. 3 is a model block diagram of the overall layout of one example ofan active-matrix type display device relating to a display device of thepresent invention;

FIG. 4 is a plan of one pixel comprised in the active-matrix typedisplay device diagrammed in FIG. 3;

FIG. 5A-5C are cross-sections in the A-A plane, B-B plane, and C-Cplane, respectively, in FIG. 4;

FIG. 6 is a cross-section of one example of a color filter in anapplication of the present invention;

FIG. 7A-7E are cross-sections representing evaluations in referenceembodiments;

FIG. 8A-8D are cross-sections of manufacturing processes in a thin filmformation method pertaining to a fourth embodiment of the presentinvention;

FIG. 9 is a characteristic diagram for describing the relationshipbetween the angle of contact and the mixture ratios of oxygen and afluorine-based compound pertaining to the theory of surface treatment inthe present invention;

FIG. 10A-10F are cross-sections of manufacturing processes in a thinfilm formation method pertaining to a fifth embodiment of the presentinvention;

FIG. 11A-11F are cross-sections of manufacturing processes in a thinfilm formation method pertaining to a sixth embodiment of the presentinvention;

FIG. 12A-12C are cross-sections (continued) of manufacturing processesin a thin film formation process pertaining to the sixth embodiment ofthe present invention;

FIG. 13 is a plan representing one extracted pixel comprised in anactive-matrix type display device pertaining to a seventh embodiment ofthe present invention;

FIG. 14A-14C are cross-sections in the A-A′ plane, B-B′ plane, and C-C′plane, respectively, in FIG. 13;

FIG. 15A-15C are cross-sections in the A-A′ plane, B-B′ plane, and C-C′plane, respectively, in FIG. 13, for describing a semiconductor layerformation process;

FIG. 16A-16C are cross-sections in the A-A′ plane, B-B′ plane, and C-C′plane, respectively, in FIG. 13; for describing a lower layer sideinsulating layer formation process;

FIG. 17A-17C are cross-sections in the A-A′ plane, B-B′ plane, and C-C′plane, respectively, in FIG. 13; for describing an upper layer sideinsulating layer formation process;

FIG. 18A-18C are cross-sections in the A-A′ plane, B-B′ plane, and C-C′plane, respectively, in FIG. 13; for describing a bank layer formationprocess;

FIG. 19A-19C are cross-sections in the A-A′ plane, B-B′ plane, and C-C′plane, respectively, in FIG. 13; for describing a surface treatmentprocess;

FIG. 20A-20C are cross-sections in the A-A′ plane, B-B′ plane, and C-C′plane, respectively, in FIG. 13; for describing an organic semiconductorfilm formation process;

FIG. 21 is a cross-section of a color filter in an application of thepresent invention;

FIG. 22 is a diagram representing changes in the angle of contact on apolyimide film surface and ITO substrate surface induced by a plasmatreatment pertaining to an eighth embodiment of the present invention;

FIG. 23[A-23E] are process cross-sections representing a method ofmanufacturing organic EL elements pertaining to a ninth embodiment ofthe present invention;

FIG. 24[A-24D] are process cross-sections representing a method ofmanufacturing a color filter pertaining to a tenth embodiment of thepresent invention;

FIG. 25[A-25D] are process cross-sections representing a manufacturingmethod for forming banks in two layers, of an inorganic substance and ofan organic substance, respectively, pertaining to an 11th embodiment ofthe present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

A first, second, and third embodiment of the present invention, as citedin claims 1-29, together with modification examples therefor, are nowdescribed.

(1) First Embodiment (Aspect Employing Ink Jet Method)

In a display device having, on a substrate, banks of a prescribedheight, and a thin film layer formed by an ink jet method on the surfaceof the substrate divided by those banks, when the width of the banks ismade a (μm), the height thereof is made c (μm), the width of the areasto be coated, divided by the banks, is made b (μm), and the diameter ofthe liquid droplets of the liquid material forming the thin film layeris made d (μm), the banks are formed on the substrate so as to satisfythe relationships a>d/4, d/2<b<5d, and c>t₀ (where t₀ is the filmthickness of the thin film layer in μm), and c>1/2×d/b.

FIG. 1 is a model diagram for describing the relationship between theliquid droplets and the banks provided on the substrate when the displaydevice of the present invention is formed by an ink jet method.

(a) Bank Configuration

The banks (also called risers or partitioning members) provided on thesubstrate used in the display device of the present invention refer topartitioning members provided for dividing pixels in a display devicewherein full color EL elements are employed, or for dividing pixel areasin color filters, for example. As diagrammed in FIG. 1, when the widthof the bank is made a (μm), it is necessary, in order for the liquidmaterial to be coated on uniformly, without overflowing into adjacentpixel areas, that the value thereof be such that a>d/4 relative to thediameter d (μm) of the liquid droplets of the liquid discharged in theink jet process, that is, that it be a value that is greater than onefourth the droplet diameter.

The banks are provided on the substrate such that their height is c(μm). It is preferable, in order to achieve the objects of the presentinvention, that the value of c (μm) be set so as to be greater than thethickness t₀ (μm) of the thin film layer to be formed, and so thatc>1/2×d/b when b (μm) is taken as the width of the area to be coated(described below), that is, that that value be greater than half theratio between the droplet diameter and the width of the area to becoated. In view of the fact that a display device should be as thin aspossible, c is made 2 microns or smaller.

In the present invention, it is desirable that, when performing coatingby an ink jet method, to provide prescribed liquid droplet reservoirs inthe bank surfaces in order to avoid color mixing due to the overflow ofliquid material into adjacent pixel areas when simultaneously coatingorganic semiconductor light emitting materials or pigments of threecolors such as red, green, and blue. It is desirable that these liquiddroplet reservoirs be provided in the upper surfaces of the banks, forexample, preferably in channel shapes in the center portions thereof.Example shapes thereof are diagrammed in FIG. 2. Specifically, FIG.2A-2C are cross-sections of banks having the liquid droplet reservoirsdescribed above, with that in FIG. 2A having a V-shaped cross-section,that in FIG. 2B having a square U-shaped cross-section, and that in FIG.2C having a rounded U-shaped or semispherical cross-section.

By providing such liquid droplet reservoirs as these, when coating isdone by the ink jet method, even if the liquid material overflows atargeted pixel it will be caught by the liquid droplet reservoir, andeven if the liquid droplets should ride up on the bank they willsimilarly be caught by the liquid droplet reservoir. As a result,display element color mixing can be avoided.

The banks are members which function as partitioning members. They maybe made of a material exhibiting liquid repellency toward the liquidmaterial. As will be described below, they may be made to exhibit liquidrepellency (Teflon-treated) by a plasma treatment. For this purpose, aninsulating organic material such as a polyimide is used which exhibitsgood bonding strength with the underlying substrate and readilyfacilitates photolithographic patterning. In color filters and the like,the partitioning members may additionally perform a shielding function.In order to form these as shielding members, a metal such as chromium oran oxide is used for the black matrix material.

The banks can be formed by any method such as lithography or printing orthe like. When a lithographic method is employed, for example, theorganic material is coated on, in conformity with the height of thebanks, by a prescribed method such as spin coating, spray coating,roller coating, die coating, or dip coating, etc., and a resist layer iscoated thereupon. By exposing and developing the resist with a maskapplied in conformity with the shape of the banks, the resist is leftremaining in conformity with the shape of the banks. Etching isperformed to remove the bank material that is not masked. Two or morelayers of banks (risers) may also be formed, with the lower layerconfigured of an inorganic substance and the upper layer of an organicsubstance.

(b) Substrate Configuration

The banks are formed on the substrate. This substrate may be a drivesubstrate whereon thin film transistors (TFTs) used in display devicesare formed, or it may be a transparent substrate used in color filters.In either case, it is desirable that the surface thereof be formed of amaterial exhibiting strong bonding strength with the banks. It isparticularly desirable that this [substrate surface] be configured of aninorganic material in order to yield suitable affinity in a surfacetreatment that will be described below. Such materials include, forexample, ITO and the like which is a transparent electrode if for adisplay device, and glass or quartz or the like if for a color filter.

(c) Configuration of Areas To Be Coated and Thin Film Layer

The display device in the present invention has a thin film layer formedby an ink jet method, using a liquid material, on the substrate surfacepartitioned by the banks described earlier, that is, in the areas to becoated. The substrate whereon those areas to be coated are formed is asdescribed in the foregoing. In the present invention, if d (μm) is takenas the diameter of the ink jet liquid droplets of the liquid materialforming the thin film layer, it is necessary to make the width b (μm) ofeach of the areas to be coated a value that is in the range d/2<b<5d.When the value of b is d/2 (μm) or less, problems ensue, such as thatthe liquid droplets overflow the areas to be coated or flow via thebanks out into the adjacent pixel areas, or as that, even when the banksexhibit liquid repellency, the liquid droplets ride up on the banks.When the value of b is 5d (μm) or greater, moreover, the liquid dropletsspread over the areas to be coated but the film thickness becomes thin,making it necessary to perform a number of repeat coatings in order toobtain the desired film thickness, which is uneconomical. In some cases,furthermore, the liquid droplets do not wet and spread uniformly.

In the present invention, if the areas to be coated, described above,are of the size noted above, there is no particular limitation on theshape thereof. That shape may be any shape at all, such as tetragonal(including rectangular, square, and diamond shaped), polygonal(pentagonal, hexagonal, etc.), a ring shape such as circular (includingperfectly circular and elliptical), cross shaped, or any other analogousshape. Nevertheless, because it is desirable that the shape be readilywettable by the liquid droplets in the coating process using an ink jetmethod, it is particularly desirable, with shapes having edges (such asthe apex point or corners in a tetragon), that those edges be curvedsurfaces. By ensuring that such is the case, when the areas to be coatedare filled in with the liquid material, those edges can be made readilywettable.

The liquid material is coated onto the areas to be coated to form a thinfilm layer. One example application is the organic EL display device.Here the thin film layer is a pixel electrode, and the liquid materialis an organic semiconductor material for forming thin film lightemitting elements. In this case, the pixel electrode is an ITO electrodefilm, for example.

(d) Surface Treatment

In the present invention, it is desirable that the substrate material ofthe areas to be coated and the banks be subjected to surface treatmentso that the bank surfaces will exhibit a higher degree of non-affinityfor the liquid material than the areas to be coated. It is preferablethat, by such surface treatment, the angle of contact of the liquidmaterial for the bank surfaces be 50 degrees or greater, and also thatthe angle of contact of the areas to be coated for the substratematerial be 20 degrees or less. By insuring that such is the case, theliquid material will not exceed and overflow the banks, even if thevolume of liquid material discharged is large compared to the thicknessof the thin film layer, and filling is done only in the prescribed areasto be coated.

For the surface treatment described above, the induction gas used may bea gas that contains fluorine or a fluorine-based compound, in anatmospheric-pressure plasma treatment or reduced-pressure plasmatreatment wherein plasma irradiation is performed in anatmospheric-pressure environment or a reduced-pressure environment,respectively, containing the fluorine-based compound and oxygen.Examples of gasses containing fluorine or a fluorine-based compoundinclude CF₄, SF₆, and CHF₃.

(e) Thin Film Formation

In the present invention, the liquid material is coated and a thin filmlayer is formed by an ink jet method in the areas to be coated that arepartitioned by the banks described earlier. By employing an ink jetmethod, any area to be coated can be filled with any quantity of liquidmaterial, and filling is even possible with a small apparatus such as isused in a home printer. In the present invention, by optimizing theshapes and sizes of the banks and the areas to be coated that arepartitioned by the banks, thin film layers are obtained wherewith nocolor mixing with neighboring pixels occurs and there is no variation infilm thickness from pixel to pixel.

The discharge quantity in the ink jet process is made such as to yieldthe desired thickness in cases where the volume declines due topost-coating heat treatment. It is permissible, depending on the case,to implement an additional deployment process after drying to obtain thedesired thickness. The normal viscosity for discharging [the liquidmaterial] from the ink jet recording head is several cP.

In the present invention, the size of the banks and the width of theareas to be coated are specified relative to the size of the liquiddroplets discharged. Therefore, even when a large volume of liquidmaterial is discharged relative to the thickness of the thin film layer,the liquid material does not exceed and overflow the banks, and theprescribed areas to be coated are filled. After the liquid material hasbeen deployed, in cases where that material contains a solvent, thesolvent component is removed by performing a heat treatment and/or areduced-pressure treatment, whereupon the volume of liquid materialdecreases and the thin film layer is formed in the areas to be coated.At this time, the surface of the areas to be coated, that is, thesubstrate surface, has been surface-treated to exhibit liquid affinity,as described earlier, wherefore the thin film layer will adhere well.The liquid material used can be an organic semiconductor material for adisplay device or a colored material or the like for a color filter. Theorganic semiconductor material used may be an organic light emittingmaterial that emits light of colors selected from among red, green, andblue, for example.

The ink jet process employed may be either a piezo-jet process or amethod that effects discharge by heat-induced foam generation. Thepiezo-jet process is to be preferred, however, in that it involves nofluid degradation due to heating.

(2) Second Embodiment (Aspect Employing Dipping or Spin-Coating Method)

The inventors discovered that, in a display device having a thin filmlayer formed by a dipping or spin-coating method, wherein banks of aprescribed height and areas to be coated partitioned by those banks areprovided on a substrate, and surface treatment is performed as desired,the objects of the present invention can be achieved even with a thinfilm formation method characterized by the fact that the thin film layeris formed using a liquid material having a surface tension of 30dyne/cm. In particular, with the display device described above, unlikein cases where coating is done using an ink jet process, the objectsmentioned can be achieved by controlling the surface energy of theliquid material in addition to the surface energy of the banks andsubstrate, without imposing any limitation whatever on the shape or sizeof the banks or areas to be coated. It is therewith possible,furthermore, to effect even finer patterning than with the ink jetmethod. In particular, by controlling the surface tension within arange, effective utilization is possible in fine patterning applicationssuch as metal wiring, etc., and patterning with a width of a few μm ispossible. This is also effective in cases where a common material isused with R, G, and B for the hole injection layers employed in themanufacture of organic EL elements.

The properties of the materials used here for the substrate, banks, andareas to be coated are the same as when coating is done using the inkjet process noted earlier. It is desirable, furthermore, that the samesurface treatment be performed on the bank surfaces and areas to becoated as in the ink jet process case. Accordingly, it is desirable thatthe substrates that are the banks and the areas to be coated eachsubtend an angle of contact of 50 degrees or greater, or 30 degrees orless, with the liquid material. The dip process and spin-coating processcan each be performed by a method commonly used in the respectivecommercial field.

(3) Third Embodiment (Specific Embodiment Aspect of Display Device)

(Configuration)

FIG. 3 is a model block diagram of the overall layout of anactive-matrix type display device in this embodiment aspect. FIG. 4 is aplan of one pixel in FIG. 3, and FIG. 5A-5C are cross-sections in theA-A plane, B-B plane, and C-C plane, respectively, in FIG. 4.

The active-matrix type display device of this embodying aspect comprisesa display unit 11 in the center portion of a transparent substrate 10.In the peripheral portion of the transparent substrate 10 is provided adata-side drive circuit 3 and a scanning-side drive circuit 4. Datalines SIG are wired to the display unit 11 from the data side drivecircuit 3, and scanning lines GATE are wired from the scanning sidedrive circuit 4. In these drive circuits 3 and 4 are configuredcomplimentary TFTs by an N-type TFT and a P-type TFT (not shown). Thesecomplementary TFTs configure shift register circuits, level shiftercircuits, and analog switch circuits, etc., configured so that they canamplify the power of data signals and scanning signals supplied from theoutside.

In the display unit 11, as in the active-matrix substrate in aliquid-crystal active-matrix type display device, a plurality of pixels7 are deployed on the transparent substrate 10. From the drive circuits3 and 4 a plurality of scanning lines GATE and a plurality of data linesSIG are wired so that they cross, with one set comprising a data lineSIG and a scanning line GATE being deployed for each pixel 7. Inaddition to the data lines SIG and scanning lines GATE that cross inmatrix fashion, a common power supply line COM is wired so as to passclose to each pixel.

Each of the pixels 7 is formed in a circular depression having adiameter of 50 μm, for example, enclosed by a bank layer. The bank layerpartitioning the pixels has a width of 10 μm and a height of 2 μm, madeof a material as previously described. A poly(para-phenylenevinyline)(PPV) precursor solution or other organic semiconductor materialsolution is used for the liquid material (wherein the PPV precursorsolution is diluted with DMF, glycerin, and diethylene glycol to make anink). This liquid material is discharged into the areas to be coatedenclosed by the banks using an ink jet process, and heated to form anorganic semiconductor film 43. The hole injection-carrier layer may havea laminar structure formed by ink-jetting or spin-coating anelectrically conductive material such as a polyethylene dioxythiophene.

Each pixel 7 comprises a conductivity control circuit 50 and a thin filmlight emitting element 40. The conductivity control circuit 50 comprisesa first TFT 20, holding capacitor CAP, and a second TFT 30. The firstTFT 20 has scanning signals supplied to the gate electrode thereof via ascanning line GATE. The holding capacitor CAP is configured so that itcan hold image signals supplied from the data line SIG via the first TFT20. The second TFT 30 has the image signals held by the holdingcapacitor CAP supplied to the gate electrode thereof. The second TFT 30and the thin film light emitting element 40 are connected in seriesbetween the common power supply line COM and an opposing electrode OP.

The first TFT 20 and second TFT 30 are formed by island-shapedsemiconductor films as diagrammed in FIG. 4 and FIG. 5A-5C. The firstTFT 20 has a gate electrode 21 configured as part of the scanning lineGATE. In the first TFT 20, a data line SIG is electrically connected toone source-drain region via a contact hole in a first interlayerinsulating layer 51, while to the other is electrically connected adrain electrode 22. To the drain electrode 22 is electrically connectedthe gate electrode 31 of the second TFT 30 via a contact hole in thefirst interlayer insulating layer 51. To one of the source-drain regionsin the second TFT 30 is electrically connected a relay electrode 35formed simultaneously with the data lines SIG, via a contact hole in thefirst interlayer insulating film 51. To the relay electrode 35 iselectrically connected a transparent electrode 41 in the thin film lightemitting element 40 via a contact hole in a second interlayer insulatingfilm 52. ITO, for example, is used for the transparent electrode.

To the other source-drain region in the second TFT 30 is electricallyconnected the common power supply line COM, via a contact hole in thefirst interlayer insulating film 51. An extension 39 of the common powersupply line COM is deployed in opposition to an extension 36 of the gateelectrode 31 of the second TFT 30, with the first interlayer insulatingfilm 51 interposed therebetween as a dielectric film, therebyconfiguring the holding capacitor CAP. This holding capacitor CAP may,instead of having the structure described above wherein it is formedbetween the common power supply line COM, be formed between the scanningline GATE and a capacitor line formed in parallel therewith.Alternatively, the holding capacitor CAP may be configured using thedrain region of the first TFT 20 and the gate electrode 31 of the secondTFT 30.

The thin film light emitting element 40 enclosed by the bank layer isformed independently in each pixel 7. In this thin film light emittingelement 40, on the upper layer side of the pixel electrode 41, theorganic semiconductor layer 43 is formed as a light emitting thin film,and the opposing electrode OP is formed, in that order, in laminarfashion. A material that emits light by the application of an electricfield, such as a poly(para-phenylene) (PPV), is used for the organicsemiconductor film 43. Instead of providing the organic semiconductorfilm 43 for each pixel, it may be formed as a stripe that crosses over aplurality of pixels 7. For the opposing electrode OP, an electricallyconductive material that reflects light, such as a film of a metal suchas aluminum containing lithium, or calcium, etc., is used. The opposingelectrode OP is formed in areas excluding the entire display unit 11 andat least that area where a terminal 12 is formed.

For the thin film light emitting element 40, a structure may be adoptedwherein a hole injection layer is deployed to enhance the light emissionefficiency (electron injection efficiency), as described in theforegoing, or a structure wherein an electron injection layer isdeployed to enhance the light emission efficiency (electron injectionefficiency), or, alternatively, a structure wherein both a holeinjection layer and an electron injection layer are formed.

(Manufacturing Method for Display Device)

A method for manufacturing an active-matrix type display device havingthe configuration described in the foregoing is next described.

Semiconductor layer formation process: First, on the transparentsubstrate 10, as necessary, an underlayer protection film is formed thatconsists of a silicon oxide film having a thickness of approximately2000 to 5000 Ångstroms. This underlayer protection film is formed by aplasma CVD method using TEOS (tetraethoxy silane) or oxygen gas as theraw material gas. Then, on the surface of this underlayer protectionfilm, a semiconductor film is formed that consists of an amorphoussilicon film having a thickness of approximately 300 to 700 Ångstroms.This semiconductor film is formed by a plasma CVD method also. Next, thesemiconductor film consisting of the amorphous silicon film is subjectedto a crystallization process using a laser annealing or fixed growthprocess or the like to crystallize the semiconductor film to apolysilicon film. Next, the semiconductor film is patterned to make anisland-like semiconductor layer. The surface thereof is then subjectedto a plasma CVD process, using TEOS (tetraethoxy silane) or oxygen gasas the raw material gas, to form a gate insulating film 37 consisting ofa silicon oxide or nitride layer having a thickness of approximately 600to 1500 Ångstroms. Next, after forming an electrically conductive filmconsisting of a film of a metal such as aluminum, tantalum, molybdenum,titanium, or tungsten, etc., patterning is performed to form the gateelectrodes 21 and 31 and the extension 36 of the gate electrode 31. Inthis process the scanning lines GATE are also formed.

In this condition, highly concentrated phosphorous ions are implanted toform source-drain regions in self-matching fashion with the gateelectrodes 21 and 31. The portions into which impurities are notintroduced become channel regions. Next, after forming the firstinterlayer insulating film 5I, the contact holes are formed, and thedata lines SIG, drain electrode 22, common power supply line COM,extension 39 of the common power supply line COM, and the relayelectrode 35 are formed. As a result, the first TFT 20, second TFT 30,and holding capacitor CAP are formed.

Next, the second interlayer insulating film 52 is formed and a contacthole is formed in this interlayer insulating film in the portioncorresponding to the relay electrode 35. Next, after forming an ITO filmover the entire surface of the second interlayer insulating film 52,patterning is performed, and a pixel electrode 42 is formed, for eachpixel 7, electrically connected to the source-drain region in the secondTFT 30 via the contact hole.

Insulating film formation process: Next, an insulating film 62 is formedalong the scanning lines GATE and data lines SIG. The insulating film 62is configured of an organic insulating material such as any of thepolyimides mentioned earlier. For the width and thickness of thisinsulating film 62, values are selected which are optimized for thediameter of the liquid droplets when the liquid material is coated on bythe ink jet process as described earlier.

Surface treatment process: Following that, a plasma treatment isconducted using a gas containing fluorine so as to effect affinity (ahydrophilic property when the liquid material contains water) in thesurface of the pixel electrode 41 for the liquid material, with theangle of contact set at 20 or lower, for example, and non-affinity inthe insulating film 62 for the liquid material, with the angle ofcontact set at 50 or higher, for example.

Organic semiconductor (organic EL element) film formation process: Afterthe surface treatment described above, the organic semiconductor films43 corresponding to R, G, and B are formed by an ink jet process in theareas to be coated partitioned in circular shapes by the banks. That is,the liquid material that is the material for configuring the organicsemiconductor film 43 is discharged from the ink jet recording head forthe circular areas to be coated enclosed by the bank layer. In aspecific example, for the red light emitting layer material, the PPVprecursor made into ink as noted above and doped with pigments such asrhodamine or beliren, or a PPV precursor (MHE-PPV) made into ink, wasused. For the material for the blue light emitting layer, a polyfluorinederivative made into ink by dissolving it in an aromatic solvent such asxyline was used. The droplet diameter thereof was 30 μmφ.

Following thereupon, in the case of a PPV precursor solution (a PPVprecursor solution diluted with DMF and made into ink), the solvent isremoved under reduced pressure, a heat treatment is performed at 150° C.to effect conjugation, and this is fixed to the areas to be coated toform the organic semiconductor film 43. Here, the sizes and shapes ofthe bank layer and areas to be coated are set at values optimized forthe 30 μmφ diameter of the liquid material droplets, wherefore the areaof coating with the organic semiconductor film 43 is definitely definedby the bank layer, and does not run out into the adjacent pixels 7. Inaddition, because the bank layer exhibits non-affinity for the liquidmaterial and the areas to be coated exhibit affinity for the liquidmaterial, the liquid material does not adhere to the side walls of thebanks. As a result, the organic semiconductor film 43 formed after heattreatment is maintained in a uniform thickness on each pixel electrodeand pixel electrode.

When the organic semiconductor film is formed as a multilayer-structureelement, moreover, as when forming a light emitting layer, holeinjection layer, and electron injection layer in laminar fashion, theliquid material deployment (using an ink jet process) and dryingoperations need only be repeated once for each layer. Alternatively,when a common material can be used for R, G, and B in the hole injectionlayer and electron injection layer, it is possible to form patterns onlyin the pixel areas, even using a spin-coating or dipping process, if thesurface tension of the liquid material is adjusted to 30 dyne/cm orless. In a specific example, a water dispersion wherein a polystyrenesulfonic acid was added to a hole injection material (such as apolythiophene derivative such as polyethyline dioxythiophene, forexample) used in an organic EL element was diluted with acellosolve-based solvent of low surface tension, or an alcohol havinglow surface tension such as methanol, or some other water-solublesolvent to adjust the surface tension to 30 dyne/cm or lower.

Such spin-coating solutions exhibited angles of contact of 60° orgreater with surface-treated (plasma-treated) banks, and of 20° orgreater with ITO surfaces.

Once the organic semiconductor films 43 are formed, the opposingelectrode OP is formed over roughly the entire surface of thetransparent substrate 10 and the active-matrix type display device iscomplete.

With a manufacturing method such as described in the foregoing, an inkjet process can be used to form the organic semiconductor films 43corresponding to R, G, and B in the prescribed areas, wherefore fullcolor active-matrix type display devices can be manufactured with highproductive yield. Also, because the organic semiconductor films can beformed with uniform thickness in each pixel, there will be noirregularities in brightness. And, because the thickness of the organicsemiconductor films is uniform, the drive current will not beconcentrated in some part of the thin film light emitting element 40,whereupon declines in the reliability of the thin film light emittingelement 40 can be prevented.

Furthermore, TFTs are formed also in the data side drive circuit 3 andscanning side drive circuit 4, but [the formation of] these TFTs isperformed by invoking all or part of the process wherein TFTs are formedin the pixels 7. Because of that, the TFTs configuring the drive circuitwill be formed between the same layers as the TFTs of the pixels 7. Thefirst TFT 20 and the second TFT 30 may, furthermore, both be N types,both be P types, or one be an N type and the other a P type.Irrespective of which of these combinations is used, however, the TFTscan be formed by a commonly known method.

(Other Modification Examples)

The present invention is not limited to or by the embodying aspectsdescribed in the foregoing, but can be implemented in variousmodifications within the scope of the present invention.

As an example, the present invention can be applied to color filters. InFIG. 6 is diagrammed a cross-section of one example of a color filterwherein the present invention is applied. In this case, a transparentsubstrate 300 made of glass or quartz is used for the substrate,partitioning members 301 formed of a resin or other black material areused for the banks, and a colored resin 302 is used for the liquidmaterial. For the partitioning members 301, a black matrix may be formedusing a black pigment or dye, or a metallic film of chromium oxide orchromium. After forming the partitioning members 301 on the transparentsubstrate 300, the areas to be coated 303 enclosed by the partitioningmembers 301 are filled with the colored resin 302 in an ink jet process.The present invention can also be employed in any other way, so long asit is obtained by filling depressions enclosed by partition-shapedmembers with any fluid, and so long as it includes a manufacturingmethod therefor.

In specific examples, the width a of the bank and the width b of theareas to be coated were varied as indicated in Table 1, display devicessuch as diagrammed in FIG. 6 were fabricated having a bank height c of 2μm, and the areas to be coated were coated with a coating liquid havinga droplet diameter d of 30 μm in an ink jet process. The results aregiven in Table 1, evaluated by the evaluation criteria noted below,under the other conditions noted below.

Bank material: Polyimide (may be a laminar bank structure usingSiO₂+polyimide)

Substrate material: ITO

Angle of contact with bank surface: 60 degrees (plasma treatment)

Angle of contact with areas to be coated: 10 degrees (plasma treatment)

Liquid material: Polyparafenylene vinylene precursor solution (an inkmade by dissolving a PPV precursor in a solution comprising mainly DMF,and adding thereto a small amount of glycerin and diethylene glycol)

Evaluation Criteria

⊚: Liquid droplets are completely accommodated in depressions withoutany residue left on the banks (cf. FIG. 7D); simultaneous discharge ofR, G, and B is possible.

◯: Liquid droplets are accommodated in depressions, but slight residueis left on banks (cf. FIG. 7C)

Δ: Liquid droplets ride up onto banks (cf. FIG. 7B); simultaneousdischarge of R, G, and B is not possible.

x: Liquid material flows over into adjacent depressions (cf. FIG. 7A);wetting does not completely spread throughout depressions (cf. FIG. 7E);even if wetting does spread, film thickness is thin, requiring multiplerepeat applications.

Table 1 [cf. orig.]

As described in detail in the first, second, and third embodiment andmodification examples thereof, it is possible with an ink jet process,by optimizing the sizes of banks and areas to be coated relative to thedroplet diameters in a liquid material, to obtain display deviceswherein there is no color mixing between pixels and extremely littlevariation in film thickness from pixel to pixel. Simultaneous R, G, andB patterning is also possible therewith.

It is further possible in a spin-coating or dip process to effect evenfiner patterning by defining the surface tension of the liquid material.

The present invention may also be effectively employed in applications,whether they be display devices or not, such as in the formation ofelectronic devices such as TFT devices on wired substrates used therein,and in organic EL devices, display devices, and color filters.

Fourth to seventh embodiments, and modification examples thereof, arenow described which embody the inventions cited in claims 30-48.

(4) Fourth Embodiment

A fourth embodiment of the present invention relates to a thin filmformation method used when forming banks of a single material.Manufacturing process cross-sections for this embodiment are diagrammedin FIG. 8A 8D. This embodiment has banks provided in any desired shapeon a bank formation surface, and may be employed in all kinds ofapplications wherein areas partitioned by banks are filled with aprescribed fluid. It is possible to employ this embodiment, for example,in cases where pixel areas are filled with an organic semiconductormaterial in a display device that uses organic semiconductor thin filmelements, and in cases where pixel areas are filled with a colored resinin color filters.

Bank formation process (FIG. 8A): The bank formation process is aprocess wherein banks are formed on a bank formation surface. The bankformation surface may be either a drive substrate whereon are formedthin film transistors (TFTs) used in display devices, or a transparentsubstrate used in a color filter. There is no limitation on thestructure of the bank formation surface so long as the objective is toform thin films by filling areas enclosed by banks that constitutepartitioning members with a fluid. It is nevertheless desirable thatthat surface be formed of a material exhibiting high bonding strengthwith the banks. It is particularly desirable that it be configured of aninorganic material in order to obtain the proper affinity in asubsequent surface treatment. This surface may be constituted of ITO iffor a transparent electrode, or of glass or crystal if for a colorfilter.

The banks are members that function as partitioning members. Thus it ispreferable that they be configured of a polyimide or other insulatingorganic material. That material may exhibit an insulating property, orthe properties of a semiconductor, or electrical conductivity. It isparticularly desirable that the banks be formed of an organic materialin order to obtain the proper non-affinity in a subsequent surfacetreatment. In a color filter or the like, the partitioning members mayalso be given a shielding function. In order to form shielding members,chromium or another metal or oxide is employed as a black-matrixmaterial. Any method may be selected for forming the banks, such as alithographic or printing method. When a lithographic method is employed,the organic material is coated on, in conformity with the height of thebanks, by a prescribed method such as spin coating, spray coating,roller coating, die coating, or dip coating, etc., and a resist layer iscoated thereupon. By exposing and developing the resist with a maskapplied in conformity with the shape of the banks, the resist is leftremaining in conformity with the shape of the banks. Etching isperformed last of all to remove the bank material that is not masked.When a printing method is used, the organic material is coated directlyin the bank shape, by any method, such as intaglio printing,planography, or relief printing. The banks 110 are formed with a heightwherewith the liquid thin film material will not overflow into adjacentdepressions, due to surface tension, when the depressions 101 enclosedby the banks are filled with the liquid thin film material. If the thinfilm layer, after heat treatment, is formed with a thickness of 0.05 μmto 0.2 μm, for example, the banks 110 are formed with a height of 1 μmto 2μ or so.

Surface treatment process (FIG. 8B): With the plasma treatment of thepresent invention, a gas containing fluorine is used as the inductiongas. This may be either a reduced-pressure plasma treatment conducted ina reduced-pressure atmosphere, or an atmospheric-pressure plasmatreatment conducted in an atmospheric-pressure atmosphere. It ispreferable that a certain amount of oxygen be present in the reactiongas. A halogen gas such as CF₄, SF₆, or CHF₃ is used as a fluorine-basedcompound.

Whether a surface is readily wettable or practically unwettable by anyfluid such as a liquid thin film material, that is, whether it exhibitsaffinity or non-affinity, can be found out by measuring the angle ofcontact subtended between the material surface and the fluid. In FIG. 9is given a diagram of measurement plots showing how the angle of contactvaries according to the mixture ratio between a fluorine-based compoundand oxygen, in cases where organic and inorganic materials are subjectedto a plasma treatment. For these measurements, the surfaces ofsubstrates over the entire surface whereof were formed a polyimide, ITO,and SiO₂ were subjected to the plasma treatment described earlier, andthe angles of contact with the inks described below were measured.

For the substrate whereon the polyimide film is formed, a PPV precursorink (wherein a PPV precursor solution is diluted with a mixed solventthe main component whereof is DMF, to which a small amount of glycerinand diethylene glycol had been added) was used.

For the substrate whereon ITO or SiO₂ is formed, an ink was used made byadding methanol, glycerin, and ethoxy ethanol to a water dispersion of ahole injection material (polyethylene dioxythiophene to which apolystyrene-sulfonic acid was added).

The angle of contact is the angle of contact with an ink or the likewhich is a fluid exhibiting affinity. CF₄ is used here for thefluorine-based compound, a polyimide for the organic material, and SiO₂and ITO (indium-tin oxide) for the inorganic material. As shown in FIG.9, there is no great difference in degree in the angle of contactexhibited by an organic material and an inorganic material in anoxygen-excessive atmosphere. However, when the amount of fluorine-basedcompound is made excessive, the angle of contact of the organic materialbecomes larger (non-affinity is exhibited). Contrariwise, there islittle change in the angle of contact of the inorganic material. Whenoxygen is contained in the reaction gas, polar groups are generated inboth the inorganic material and the organic material due to theoxidizing action of the oxygen. When the amount of the fluorine-basedcompound is excessive, however, that fluorine-based compound willpenetrate into the organic material, wherefore, it is believed, theeffect of the polar groups is relatively lessened. Accordingly, byconducting the plasma treatment under controlled conditions wherewiththe fluorine-based compound is excessive compared to oxygen, it ispossible to impart to both the organic material and the inorganicmaterial, respectively, the desired angles of contact (affinity) inaccordance with FIG. 9. It is particularly desirable, in order tomaximize the difference in angle of contact between the two, to use thebest mixture ratio (CF₄/(CF₄+O₂)=75%) in FIG. 9 or to introduce amixture gas of CF₄ and He under atmospheric pressure.

In view of the facts stated above, either a reduced-pressure plasmatreatment or atmospheric-pressure plasma treatment is conducted so thata fluorine-based compound is made the induction gas and oxygen is mixedtherein in a certain proportion. As diagrammed in FIG. 8B, for example,with a capacity-coupled plasma treatment, the gas noted above is made toflow into the reaction chamber, a substrate having the bank formationsurface 100 is loaded onto one electrode, and an electric field isapplied between the other electrode 201 from a power supply 200. Also,if the conditions are selected for the angle of contact of the banks 110such that the angle of contact at the extreme edges does not becomelarge, a thin film layer 204 can be formed with a nearly uniform filmthickness without being repelled by the extreme edges at the side wallsof the banks 110. The quantity of the liquid thin film material 203discharged is adjusted so that the thickness of the thin film layer 204after formation becomes 0.1 μm to 2 μm or so.

The ink jet process used may be a piezo-jet process or a process thateffects discharge by the generation of foam by heat. The piezo-jetprocess involves a configuration wherein a nozzle and a piezoelectricelement are comprised in a pressure chamber. When a voltage is appliedto a piezoelectric element loaded with a fluid in the pressure chamber,the pressure chamber undergoes a volumetric change, and fluid dropletsare discharged from the nozzle. With the process that discharges by foamgeneration, a heating element is provided in the pressure chamber thatcommunicates with a nozzle. Therewith, the heating element is made toemit heat, thereby vaporizing the fluid in the vicinity of the nozzle,thus generating foam, by the volumetric expansion whereof the fluid isdischarged. The piezo-jet process is preferable in view of fact thattherewith there is no degradation caused in the fluid by heating.

When this embodiment, as described in the foregoing, is implemented,plasma treatment is conducted under conditions wherein oxygen is mixedinto a fluorine-based compound. Therefore, in one quick operation,surface treatment can be performed to effect non-affinity for the liquidthin film material in the bank surfaces and affinity therefor in thebank formation surface. In addition, the angles of contact can readilybe set so as to exhibit degrees of affinity according to thecharacteristics plotted in FIG. 9. That is, the affinities of both thebank and the bank formation surface can be definitely controlled, whilemaintaining high bonding strength between the banks themselves and thebank formation surface, without having to negotiate numerous processesas required conventionally for affinity control. Thus the liquid thinfilm material can be prevented from overflowing the banks, product yieldcan be improved, and manufacturing costs can be reduced.

(5) Fifth Embodiment

A fifth embodiment of the present invention relates to a thin filmformation method used when forming banks in a two-layer structure. Thisembodiment is particularly characterized by the fact that the lowerlayer is formed of an inorganic material and the upper layer is formedof an organic material.

Manufacturing process cross-sections for this embodiment are given inFIG. 10A-10F. This embodiment, as the fourth embodiment, can be employedin all kinds of applications wherein banks are provided in any desiredshape on a bank formation surface, and areas partitioned by banks arefilled with a prescribed fluid. It can be employed, for example, incases where, in a display device wherein organic semiconductor thin filmelements are used, pixel areas are filled with an organic semiconductormaterial, and in cases where, in a color filter, pixel areas are filledwith colored resin.

Lower layer film formation process (FIG. 10A): The lower layer filmformation process is a process for forming a lower layer film 120 on abank formation surface 100. The bank formation surface is the same as inthe fourth embodiment described above. It is desirable that the materialof the lower layer film be composed of an inorganic material in order toobtain good non-affinity in a subsequent surface treatment. It is alsodesirable that this material exhibit good bonding strength with the bankformation surface 100. In cases where the bank formation surface isformed of ITO or the like, for example, it is possible to use ordinarysilicon oxide (SiO₂), a silicon nitride film, or amorphous silicon. Whensuch a material is used, affinity is obtained by plasma treatment thatis between the affinity of the bottom surface of the depressions 101 andthe affinity of the upper bank surfaces 121. This affinity is effectivein causing the liquid thin film material to flatly and securely adhereto the bottom surface of the depressions 101. The lower layer film isformed by coating the inorganic material described above by a prescribedmethod such as spin coating, spray coating, roller coating, die coating,or dip coating, etc., adjusted to a desired height. It is preferablethat the height of the lower layer film 120 be roughly the same as theheight of the thin film layer 204. Because the lower layer film 120exhibits some degree of affinity with the liquid thin film material 203,the liquid thin film material 203 and the wall surfaces of the lowerlayer film 120 will bond together when the liquid thin film material 203is subjected to heat treatment. This is because, if the final thicknessof the liquid thin film material 203 and the height of the lower layerfilm 120 are made roughly equal, the distortion in the surface of thethin film layer 204 induced by the bonding of the liquid thin filmmaterial 203 to the wall surface of the lower layer film 120 can beeliminated.

Upper layer formation process (FIG. 10B): The upper layer formationprocess is a process for forming the upper bank layer 121 on the lowerlayer film 120. The organic materials listed for the fourth embodimentdescribed above are used for the material of the upper bank layer 121.It is also possible to make this do double duty as a shielding material.The upper bank layer 121 is selectively formed in areas where banks areto be formed. Any process can be selected, such as a printing process orlithographic process, etc. When a printing method is used, the organicmaterial is coated directly in the bank shape, by any method, such asintaglio printing, planography, or relief printing. When a lithographicmethod is employed, the organic material is coated on, in conformitywith the height of the upper bank layer 121, by a prescribed method suchas spin coating, spray coating, roller coating, die coating, or dipcoating, etc., and a resist layer is coated thereupon. By exposing anddeveloping the resist with a mask applied in conformity with the shapeof the banks, the resist is left remaining in conformity with the shapeof the banks. Etching is performed last of all to remove the material ofthe upper bank layer that is not masked. The banks 110 are formed with aheight wherewith the liquid thin film material will not overflow intoadjacent depressions, due to surface tension, when the depressions 101enclosed by the banks are filled with the liquid thin film material. Ifthe thin film layer, after heat-treatment, is formed with a thickness of0.05 μm to 0.2 μm, for example, the matched heights of the lower layerfilm 120 and the upper bank layer 121 are formed at a height of 1 μm to2 μm or so.

Removal process (FIG. 10C): The removal process is a process for etchingthe lower layer film using the upper bank layer 121 as a mask. The upperbank layer 121 is an organic material and can act as a resist . . . Thatbeing so, it is possible to selectively etch only the lower layer film120 by selecting the etching material. For example, the upper bank layer121 is formed beforehand to a thickness greater than the thicknesssought, and the entirety of the lower layer film is dry-etched, or, whenthe lower layer film 120 is formed of SiO₂, wet etching is performedusing hydrofluoric acid as the etching agent. In this process the lowerlayer film 120 is removed except in the bank formation areas masked bythe upper bank layer 121.

Surface treatment process (FIG. 10D): The surface treatment process is aprocess wherein a plasma process is conducted under certain conditionsto adjust the affinity of the bank formation surface 100, the lowerlayer film 120, and the upper bank layer 121 for the liquid thin filmmaterial. The plasma treatment in the present invention is performedunder the same conditions and using the same gas as in the firstembodying aspect described earlier. In particular, if ITO and SiO₂ areselected for the bank formation surface 100 and the lower layer film120, respectively, good affinity setting can be performed by thissurface treatment. That is, as is shown in FIG. 9, since ITO and SiO₂are both inorganic materials, the variation characteristics arising fromthe mixture ratio between the fluorine-based compound and oxygen aresimilar, but SiO₂ exhibits a higher affinity trend. For this reason,surface treatment can be performed so that the order of affinity degreein the bank formation surface 100, lower layer film (lower bank layer)120, and upper bank layer 121 becomes “bank formation surface≧lower banklayer surface>upper bank layer surface.”

Thin film formation process (FIG. 10E, 10F): The thin film formationprocess is a process for forming a thin film layer by filling thedepressions 101 enclosed by the lower bank layer 120 and the upper banklayer 121 with the liquid thin film material 203. The details of thisprocess are the same as in the fourth embodiment described earlier.After the liquid thin film material 203 is deployed, the solventcomponent is vaporized in a heat treatment or the like to form the thinfilm layer 204.

As diagrammed in FIG. 10E, the liquid thin film material 203 isdischarged from an ink jet recording head 202 into the depressions 101.The discharge quantity is adjusted to a quantity wherewith the desiredthickness is obtained after the volume has been reduced by heattreatment. It is preferable, for the reason stated earlier, that thisthickness be approximately the same as the thickness of the lower banklayer 120. Even when the liquid thin film material 203 is discharged ina large volume as compared to the thickness of the thin film layer 204,as diagrammed in FIG. 10E, the surface tension of the upper bank layer121 acts so that the liquid thin film material 203 mounds up, whendeployed, to the S3 position, without overriding the banks. Once theliquid thin film material has been deployed, a heat treatment or thelike is performed to vaporize the solvent component. By thisvaporization of the solvent component, the volume of the liquid thinfilm material 203 decreases, as diagrammed in FIG. 10F, whereupon thethin film layer 204 is formed with its thickness at S4 on the bottomsurface of the depression 101, which thickness is on the same order asthat of the lower bank layer 120. At this time, since the bottom of thedepressions 101, which is the bank formation surface 100, has beensurface-treated to exhibit affinity, the thin film layer 204 exhibitsgood wetting. The angle of contact of the lower bank layer 120 issmaller than that of the upper bank layer 121, moreover, whereupon itbonds with the liquid thin film material 203 with suitable affinity. Forthis reason, the liquid thin film material 203 is not repelled by theside walls of the lower bank layer 120. The lower bank layer 120 and thethin film layer 204 have nearly the same thickness, moreover, whereforethe liquid thin film material 203 is not pulled away to the side wallsof the lower bank layer 120. For this reason, the thin film layer 204 isformed with a nearly uniform film thickness. The quantity of liquid thinfilm material 203 discharged is adjusted so that the thickness of thethin film layer 204 after formation becomes 0.1 μm to 2 μm or so.

By implementing this embodiment, as described in the foregoing, theaffinities of the upper bank layer, lower bank layer, and bank formationsurface can be set so as to rise, in that order, by conducting a plasmatreatment under the condition that oxygen is mixed into thefluorine-based compound, in banks laminated of an inorganic material andan organic material. That is, it is possible to terminate the surfacetreatments at one time by controlling a simple plasma treatment, whilemaintaining high bonding strength between the banks themselves and thebank formation surface, without undergoing numerous processes asrequired conventionally for affinity control. Thus the liquid thin filmmaterial can be prevented from overflowing the banks, product yield canbe improved, and manufacturing costs can be reduced. In particular, thebenefit of being able to form uniform thin film layers is realized.

(6) Sixth Embodiment

A sixth embodiment of the present invention forms banks in a two-layerstructure by a method differing from that of the fifth embodimentdescribed above.

Manufacturing process cross-sections for this embodiment are diagrammedin FIG. 11A-11F and FIG. 12A-12C. This embodiment, as the fourthembodiment, can be employed in all kinds of applications wherein banksare provided in any desired shape on a bank formation surface, and areaspartitioned by banks are filled with a prescribed fluid. It can beemployed, for example, in cases where, in a display device whereinorganic semiconductor thin film elements are used, pixel areas arefilled with an organic semiconductor material, and in cases where, in acolor filter, pixel areas are filled with colored resin. The materialsfor and thicknesses of the bank formation surface, lower layer film, andupper bank layer are the same as in the fourth and fifth embodimentsdescribed earlier, and so are not further described here.

Lower layer film formation process (FIG. 11A): The lower layer filmformation process is a process for forming a lower layer film 130 on thebank formation surface 100. The lower layer film 130 is formed by thesame method as in the fifth embodiment described earlier.

Exposure process (FIG. 11B): This exposure process is a process forexposing the lower layer film 130 matched to the shape of the banks. Amask 132 matched to the shape of the banks is deployed on the upperportion of the lower layer film 130. In cases where the lower layer film130 is a material that is hardened by the application of energy, maskingis done so that light passes through to the bank formation areas but notthrough to the areas to be removed. In cases where the lower layer film130 is a material that is degraded so as to be removable by theapplication of energy, masking is done so that light is interrupted tothe bank formation areas but passed through to the areas to be removed.It is possible to etch the lower layer and upper layer independently,wherefore the shapes of the banks in the lower layer and in the upperlayer, respectively, can be made to differ. By suitably selecting theshape of the lower bank layer, it becomes possible to suitably deploythe thin film layer. Exposure is made using a known method such as oneemploying a laser beam or other energy source.

Etching process (FIG. 11C): This etching process is a process forremoving the lower layer film 130 so as to leave the areas hardened byexposure. After the exposure is made, the mask and the areas to beremoved in the lower layer film 130 are removed using a solvent. WhenSiO₂ or a polysilazane is used for the lower layer film 130, etching isperformed using hydrofluoric acid as the etching agent. Dry etching mayalso be used.

Upper layer film formation process (FIG. 11D): The upper layer filmformation process is a process for forming the upper layer film 130 sothat it covers the lower bank layer 130. The upper layer film 131 isformed by the same process as the lower layer film 130, described above.

Exposure process (FIG. 11E): This exposure process is a process forexposing the upper layer film 131 in conformity with the shape of theupper layer banks. A mask 134 is deployed on the upper layer film 131 soas to match the shape of the upper bank layer. In cases where the upperlayer film 131 is a material that is hardened by the application ofenergy, masking is done so that light passes through to the bankformation areas but not through to the areas to be removed. In caseswhere the upper layer film 131 is a material that is degraded so as tobe removable by the application of energy, masking is done so that lightis interrupted to the bank formation areas but passed through to theareas to be removed. In this embodiment, as described in the foregoing,the shape of the upper bank layer 131 may be made to differ from that ofthe lower layer. Exposure may be made using a known method such as oneemploying a laser beam or other energy source.

Etching process (FIG. 11F): This etching process is a process forremoving the upper layer film 131 so as to leave the areas hardened byexposure. After the exposure is made, the mask and the areas to beremoved in the upper layer film 131 are removed using a solvent. When apolyimide is used for the upper layer film 131, etching is performedusing hydrofluoric acid as the etching agent. Dry etching may also beused.

Surface treatment process (FIG. 12A): The surface treatment process isthe same as in the fifth embodiment, described earlier, wherefore nofurther description thereof is given here. With this surface treatment,surface treatment can be performed so that the order of affinity degreein the bank formation surface 100, lower layer film 130, and upper banklayer 131 becomes “bank formation surface≧lower bank layer surface>upperbank layer surface.”

Thin film formation process (FIG. 12B, 12C): The thin film formationprocess is a process for forming a thin film layer by filling thedepressions 101 enclosed by the lower bank layer 130 and the upper layer131 with the liquid thin film material 203. This thin film formationprocess is the same as in the fifth embodiment, described earlier,wherefore no further description thereof is given here.

By implementing this embodiment, as described in the foregoing, theaffinities of the upper bank layer, lower bank layer, and bank formationsurface can be set so as to rise, in that order, by conducting a plasmatreatment under the condition that oxygen is mixed into thefluorine-based compound, in banks laminated of an inorganic material andan organic material. That is, it is possible to terminate the surfacetreatments at one time by controlling a simple plasma treatment, whilemaintaining high bonding strength between the banks themselves and thebank formation surface, without undergoing numerous processes asrequired conventionally for affinity control. Thus the liquid thin filmmaterial can be prevented from overflowing the banks, product yield canbe improved, and manufacturing costs can be reduced. In particular, thebenefits of being able both to form uniform thin film layers and to formthe lower bank layer and upper bank layer in differing shapes arerealized.

(7) Seventh Embodiment

A seventh embodiment relates to a display device that is manufactured byapplying the fifth embodiment described earlier to an actual displaydevice.

(Overall Configuration)

This display device is an active-matrix type display device, the overallconfiguration whereof is the same as that diagrammed in FIG. 3 describedearlier. (For this reason, the same symbols are used for the configuringelements as in FIG. 3, and no further description is given here ofcoinciding components.) FIG. 13 is a plan representing one extractedpixel comprised therein, and FIG. 14A-14C are cross-sections in the A-A′plane, B-B′ plane, and C-C′ plane, respectively, in FIG. 13.

The overall configuration of this active-matrix type display device 1 isthe same as or equivalent to that diagrammed in FIG. 3, describedearlier. The points of difference are as follows.

Each of the pixels 7 is formed as a depression enclosed by a bank layerBANK. This bank layer is configured in laminar fashion with a lowerlayer side insulating film 61 and an upper layer side insulating film62. A third embodying aspect is employed in the application of this banklayer BANK. The material and height thereof, etc., are the same as inthe third embodying aspect. An organic semiconductor material is used asthe liquid thin film material. The organic semiconductor film 43 isformed by discharging this material into the areas enclosed by the banklayer BANK and then heating it. If [the thickness of] this organicsemiconductor film 43 is 0.05 μm to 0.2 μm, the lower layer sideinsulating film 61 and the upper layer side insulating film 62 areformed so that [their thicknesses] become approximately 0.2 μm to 1.0μm, and 1 μm to 2 μm, respectively.

The first TFT 20 and the second TFT 30 are formed by island-shapedsemiconductor films as diagrammed in FIGS. 7 and 8. For the organicsemiconductor film 43, a material that emits light with the applicationof an electric field, such as a polyphenylene vinylene (PPV), forexample, is used.

(Bank Layer Action)

With the configuration described above, the bank layer BANK is subjectedto a plasma treatment using fluorine or a fluorine-based compound as theinduction gas, as in the embodiment aspects described earlier, prior todeploying the organic semiconductor material 203 in an ink jet process.For this reason, affinity for the organic semiconductor material isformed in the order pixel electrode 41≧lower layer side insulating filmlayer 62>upper layer side insulating film layer 62. For this reason,even if the pixel areas enclosed by the bank layer BANK are filled upcompletely with the liquid thin film material containing the organicsemiconductor material, the organic semiconductor film 43 will settle atthe height of the lower layer side insulating layer 62, the organicsemiconductor film 43 can be prevented from hardening in a U-shape, anda flat organic semiconductor film 43 can be formed. When some portion ofthe organic semiconductor film 43 has a thin film thickness, the drivecurrent of the thin film light emitting element 40 will be concentratedthere, and the reliability of the thin film light emitting element 40will decline, but such problems can be eliminated.

In this embodiment, furthermore, the bank layer BANK is also formed inareas, within the area where the pixel-electrode 41 is formed, whichoverlap the relay electrode 35 of the conductivity control circuit 50,and the organic semiconductor film 43 is not formed in areas whichoverlap the relay electrode 35. That is, the organic semiconductor film43 is only formed in the flat portions of the area where the pixelelectrode 41 is formed. This is also a factor in maintaining the organicsemiconductor film 43 at a certain film thickness.

If there is no bank layer BANK in the areas overlapping the relayelectrode 35, in that portion also the drive current will flow betweenthe opposing electrode OP, and the organic semiconductor film 43 willemit light. However, this light will be trapped between the relayelectrode 35 and the opposing electrode OP so that it is not emitted tothe outside and does not contribute to the display. Such a drive currentthat flows in a portion that does not contribute to the display may betermed ineffective current in terms of the display. Hence, in thisaspect, the bank layer BANK is formed in portions where conventionallysuch ineffective current should flow. Nevertheless, wasted current canbe prevented from flowing to the common power supply line COM, whereuponthe width of the common power supply line COM can be made that muchnarrower. As a result, the light emitting surface area can be increased,and such display performance parameters as brightness and contrast ratiocan be improved.

It is also possible to form organic semiconductor films that aredeployed separately for each primary color, employing an ink jetprocess, wherefore patterning is possible without employing acomplicated process such as a photolithographic process.

The bank layer BANK may also be formed by a black resist. The bank layerBANK thereupon functions as a black matrix, and such display qualitiesas contrast ratio are improved. More specifically, with theactive-matrix type display device 1 to which this aspect pertains, theopposing electrode OP is formed over the entire surface of the pixel 7on the front side of the transparent substrate 10, wherefore the lightreflected by the opposing electrode OP causes the contrast ratio todecline. That notwithstanding, if a bank layer BANK which functions alsoto reduce parasitic capacitance is configured by a black resist, thatbank layer BANK can be made to function as a black matrix, and to blockthe reflected light from the opposing electrode OP, wherefore thecontrast ratio can be improved.

The bank layer BANK is formed along the data line SIG and the scanninglines GATE, thicker than the organic semiconductor film 41, and thereonis formed the opposing electrode OP. Therefore, due to the presence ofthe bank layer BANK, large capacitances can be prevented from becomingparasitic on the data line SIG. That is, because the thick bank layerBANK is also interposed between the data line SIG and the opposingelectrode OP, the parasitic capacitance produced in the data line SIG isextremely small. Because of that fact, the loads on the drive circuits 3and 4 can be reduced, and it becomes possible to effect low powerconsumption operation and/or faster display operations.

The bank layer BANK, furthermore, is configured in a two-layer structurecomprising an inorganic material and an organic material. If an attemptis made to form a thick bank layer of only an inorganic material, itbecomes necessary to form the film from the inorganic material by aPECVD process or the like, which requires a long process time. Incontrast thereto, it is easy to form a comparatively thick film of anorganic material in a resist or polyimide layer. The bank layer BANK inthis embodying aspect is constituted of an organic material wherewith itis easy to make the upper layer side insulating film 62 a thick film.Hence the bank layer formation can be concluded in a short time andproductivity thus enhanced.

If such a two-layer structure is effected, moreover, the organicsemiconductor film 41 comes in contact with the lower layer sideinsulating film made of the inorganic material, but it does not come incontact with the upper layer side insulating film 62 made of the organicmaterial. Because of that, the organic semiconductor film 41 will notdeteriorate under the influence of the upper layer side insulating film62 configured of the organic material, wherefore, in the thin film lightemitting element 40, there is no decline in either light emittingefficiency or reliability.

As based on this embodiment, the bank layer BANK is formed also in theperipheral areas of the transparent substrate 10 (that is, in areasexterior to the display unit 11), wherefore both the data side drivecircuit 3 and the scanning side drive circuit 4 are covered by the banklayer BANK. It is sufficient that the opposing electrode OP be formed atleast in the display unit 11, with no necessity of forming it all theway to the drive circuit areas. However, when the opposing electrode OPis formed using a mask-sputtering process, matching precision is poor,wherefore the opposing electrode OP is sometimes formed all the way tothe drive circuit areas. In this embodiment, even should the opposingelectrode OP be formed all the way to the drive circuit areas, the banklayer BANK will be interposed between the drive circuit interconnectionlayer and the opposing electrode OP. Hence capacitances can be preventedfrom becoming parasitic in the drive circuits 3 and 4, the loads onthose drive circuits 3 and 4 can be reduced, and it is possible toeffect lower poser consumption and/or faster display operation.

(Display Device Operation)

In the active-matrix type display device 1 configured as described inthe foregoing, when the first TFT 20 is selected and turned on by ascanning signal, an image signal from the data line SIG is applied tothe gate electrode 31 of the second TFT 30 via the first TFT 20. At thesame time, the image signal will be written to the holding capacitor CAPvia the first TFT 20. As a result, when the second TFT 30 is turned on,a voltage is applied, with the opposing electrode OP and the pixelelectrode 41 serving as the negative electrode and positive electrode,respectively, whereupon, in the area where the applied voltage exceedsthe threshold voltage value, the current flowing to the organicsemiconductor film 43 (the drive current) will increase very rapidly.Accordingly, the light emitting element 40 emits light as anelectro-luminescence device or LED device. The light from the lightemitting element 40 is reflected by the opposing electrode OP, passedthrough the transparent pixel electrode 41 and the transparent substrate10, and ejected. The drive current for effecting this light emissionflows through a current path configured by the opposing electrode OP,the organic semiconductor film 43, the pixel electrode 41, the secondTFT 30, and the common power supply line COM, and will therefore ceaseflowing when the second TFT 30 is turned off. However, because the gateelectrode of the second TFT 30 is maintained at an electrical potentialcorresponding to the pixel signal by the holding capacitor CAP, evenwhen the first TFT 20 is turned off, the second TFT 30 remains in the onstate. Hence the drive current will continue flowing to the lightemitting element 40, and this pixel will remain in the lighted state.This state is maintained until new image data are written to the holdingcapacitor CAP and the second TFT 30 is turned off.

(Display Device Manufacturing Method)

Next, a method for manufacturing the active-matrix type display deviceconfigured as described in the foregoing is described while referencingFIG. 15A-15C to FIG. 20A-20C. This manufacturing method employs themanufacturing method of the fifth embodiment for the display device.

Semiconductor layer formation process (FIG. 15A-15C): First, afterforming an underlayer protection film (not shown) consisting of asilicon oxide film having a thickness of approximately 2000 to 5000Ångstroms in a plasma CVD process using TEOS (tetraethoxy silane) oroxygen gas, etc., as the raw material gas, as necessary, on thetransparent substrate 10, a semiconductor film consisting of anamorphous silicon film having a thickness of approximately 300 to 700Ångstroms is formed in a plasma CVD process on the back side of theunderlayer protection film. Next, the semiconductor film consisting ofthe amorphous silicon film is subjected to a crystallization processsuch as laser annealing or a solid phase growing process, therebycrystallizing the semiconductor film to a polysilicon film. Next, thesemiconductor film is patterned to yield an island-shaped semiconductorfilm, on the surface whereof is then formed a gate insulating film 37consisting of a silicon oxide or nitride film having a thickness ofapproximately 600 to 1500 Ångstroms in a plasma CVD process using TEOS(tetraethoxy silane) or oxygen gas, etc. Next, after forming anelectrically conductive film consisting of a film of metal such asaluminum, tantalum, molybdenum, titanium, or tungsten, by a sputteringprocess, patterning is performed to form the gate electrodes 21 and 31and the extension 36 of the gate electrode 31. The scanning line GATE isalso formed in this process.

In this condition, highly concentrated phosphorous ions are implanted toform source-drain regions in self-matching fashion with the gateelectrodes 21 and 31. The portions into which impurities are notintroduced become channel regions. Next, after forming the firstinterlayer insulating film 51, the contact holes are formed, and thedata lines SIG, drain electrode 22, common power supply line COM,extension 39 of the common power supply line COM, and the relayelectrode 35 are formed. As a result, the first TFT 20, second TFT 30,and holding capacitor CAP are formed.

Next, the second interlayer insulating film 52 is formed and a contacthole is formed in this interlayer insulating film in the portioncorresponding to the relay electrode 35. Next, after forming an ITO filmover the entire surface of the second interlayer insulating film 52,patterning is performed, and a pixel electrode 41 is formed, for eachpixel 7, electrically connected to the source-drain region in the secondTFT 30 via the contact hole.

Lower layer side insulating film formation process (FIG. 16A-16C): Next,a film (an inorganic film for forming the lower layer side insulatingfilm 61) consisting of an inorganic material is formed in a PECVDprocess or the like on the front surface of the second interlayerinsulating film 52. This film is formed of the inorganic material and tothe thickness described in the embodying aspect described earlier. Thisfilm is formed to a thickness that is greater than the thickness of theorganic semiconductor film 41. If the organic semiconductor film 41 isformed to a thickness of 0.05 μm to 0.2 μm, for example, the film ofinorganic material is formed to a thickness of approximately 0.2 μm to1.0 μm.

Upper layer side insulating film formation process (FIG. 17A-17C): Aresist (upper layer side insulating film 62) is then formed along thescanning line GATE and the data line SIG. This upper layer sideinsulating film 62 is configured of the organic material of theembodying aspect described earlier. The thickness of the upper layerside insulating film 62 is formed to a height wherewith it can become abulwark of such extent that the liquid thin film material will notoverflow into the adjacent pixel areas even when the pixel area isfilled with the liquid thin film material. If the organic semiconductorfilm 41 is formed to a thickness of 0.05 μm to 0.2 μm, or example, theupper layer side insulating film 62 is formed to a height of 1 μm to 2μm or so.

Removal process (FIG. 18A-18C): Next, the upper layer side insulatingfilm 62 is masked and the layer consisting of the inorganic material ispatterned. As a result, the film consisting of the inorganic materialremains along the scanning like GATE and the data line SIG, and thelower layer side insulating film 61 is formed. Thus the bank layer BANKis formed in a two-layer structure comprising a lower layer sideinsulating film 61 and an upper layer side insulating film 62. At thistime, the portion of the resist remaining along the data line SIG ismade wide so as to cover the common power supply line COM. As a result,the area where the organic semiconductor film 43 of the light emittingelement 40 is to be formed is enclosed by the bank layer BANK.

Surface treatment process (FIG. 19A-19C): Next, a plasma process isadministered, using fluorine, to impart affinity for the liquid thinfilm material (or a hydrophilic property when the liquid thin filmmaterial contains water) to the surface of the pixel electrode 41,non-affinity for the liquid thin film material to the upper layer sideinsulating film 62, and an affinity therebetween to the lower layer sideinsulating film 61. The specific method used is the same as in thefourth and fifth embodiments.

Thereby, surface treatment is performed so that the order of affinitydegree in the lower layer side insulating film 61 (inorganic material)and the upper layer side insulating film 62 (organic material) becomes“pixel electrode surface≧lower layer side insulating film surface>upperlayer side insulating film surface.”

Organic semiconductor film formation process (FIG. 20A-20C): As soon asthe surface treatment described above is finished, organic semiconductorfilms 43 corresponding to R, G, and B are formed in an ink jet processin the areas demarcated in matrix-fashion by the bank layer BANK. Inthis operation, the liquid thin film material 203 that is the liquidmaterial (precursor/discharge liquid) for configuring the organicsemiconductor layers 43 is discharged from the ink jet recording head202 onto the areas on the inside of the bank layers BANK. Next, a heattreatment is administered at a temperature of 100° C. to 150° C. tovaporize the solvent component in the liquid thin film material and formthe organic semiconductor films 43 securely in the areas inside the banklayers BANK. These bank layers BANK have been surface-treated as notedabove and therefore exhibit water repellency. For the liquid thin filmmaterial of the organic semiconductor film 43, that is the precursor ofthe organic semiconductor film 43, on the other hand, a hydrophilicsolvent is used, wherefore the areas coated by the organic semiconductorfilms 43 are definitely defined by the bank layer BANK, and there is nooverflow into the adjacent pixels 7. In addition, because the side wallsof the bank layer BANK are water-repellent, the liquid thin filmmaterial will not adhere to the side walls, even when the solventcomponent of the liquid thin film material is vaporized by heattreatment so that the volume of the liquid thin film material decreases,and the contact surface between the liquid thin film material and theside walls will move to the pixel electrode 41 and the inorganicmaterial areas which are more hydrophilic. Accordingly, in the organicsemiconductor films 43 formed after the heat treatment, uniformthickness will be maintained on the pixel electrode, without thickeningat the periphery. In cases where a multi-layer structure element isformed, moreover, it is only necessary to repeat the processes of liquidthin film material deployment, by the ink jet process, and of drying,for each layer. This would be a case where, for example, a lightemitting film, hole injection layer, and electron injection layer areformed in laminar fashion for the organic semiconductor layer.

In the process described above, furthermore, a hole carrier layer mayalso be formed by an ink jet method. A liquid thin film material fromwhich the hole carrier layer will originate can be deployed in pixelareas enclosed by a bank layer to a thickness of 3 μm to 4 μm, forexample. When this liquid thin film material is heat-treated, a holecarrier layer having a thickness of 0.05 μm to 0.1 μm or so can beformed. Once this hole carrier layer is formed, the organicsemiconductor material is deployed to a similar thickness in another inkjet process.

Once the organic semiconductor layers 43 are formed, the opposingelectrode OP is formed over roughly the entire surface of thetransparent substrate 10 and the active-matrix type display device 1 iscomplete (cf. FIG. 14A-14C).

By implementing a manufacturing method such as described in theforegoing, each of the organic semiconductor film 43 corresponding to R,G, and B can be formed in prescribed areas using an ink jet process,wherefore the full-color active-matrix type display device 1 can bemanufactured with high productive yield. The organic semiconductorlayers can be formed with uniform thickness, moreover, whereforebrightness irregularities do not occur. Also, because the thickness ofthe organic reflecting layer films is uniform, the drive current willnot be concentrated in one portion of the thin film light emittingelement 40, wherefore the reliability of the thin film light emittingelement 40 can be prevented from declining.

Furthermore, although TFTs are formed in the data side drive circuit 3and the scanning side drive circuit 4 diagrammed in FIG. 13, this isdone by invoking the process of forming the TFTs in the pixels 7, inwhole or in part. For that reason, the TFTs that configure the drivecircuits will be formed between the same layers as the TFTs of thepixels 7. The first TFT 20 and the second TFT 30, moreover, may both beN types or both P types, or one may be an N type and the other a P type.With any of these combinations, however, the TFTs can be formed by aknown process, wherefore no further description thereof is given here.

(Other Modification Examples)

The inventions described in claims 31-49 are not limited to or by thefourth to seventh embodiments, but can be applied in variousmodifications within the scope of the essential invention.

The seventh embodiment herein, for example, is an application of thepresent invention to a display device, but it may also be applied to acolor filter as diagrammed in FIG. 21. In that case, a transparentsubstrate 300 consisting of glass or quartz is used for the bankformation surface, partitioning members 301 formed of a black materialsuch as a resin are used for the banks, and a colored resin 302 is usedor the liquid thin film material. The partitioning members 301 may beformed as a black matrix wherein a black pigment or dye, or a chromiumoxide or chromium metal film, etc., is employed. After forming thepartitioning members 301 on the transparent substrate 300, an ink jetprocess is used to fill depressions 303 enclosed by the partitioningmembers 301 with the colored resin 302. This invention can also beemployed in other applications so long as it is a manufacturing methodwherein depressions enclosed by partition-shaped members are filled witha fluid, which fluid may be any fluid.

The surface treatment, moreover, is not limited to a plasma treatment,but any surface treatment method can be employed so long as therewithdifferent affinities can be processed under the same surface treatmentconditions, as graphed in FIG. 9. That is because the main concept inthis invention is that of being able to set a plurality of affinities atone time in one surface process. Accordingly, the materials for whichaffinities are set are not limited to an inorganic material and anorganic material, and this invention can be applied to surfacetreatments between any specific materials so long as the affinitycharacteristics graphed in FIG. 9 are exhibited between those specificmaterials.

As based on the fourth to seventh embodiments and modification examplesthereof, as set forth in the foregoing, plasma treatments areadministered under certain conditions, it is possible to definitelycontrol the affinities in banks and bank formation surfaces, whilemaintaining high bonding strength in the banks themselves for the bankformation surfaces, without involving numerous process steps to effectaffinity control. Thus product yield can be raised and manufacturingcosts reduced.

As based on the display devices [of the present invention], furthermore,the affinities of the banks and the bank formation surfaces aredefinitely set by administering plasma treatments under certainconditions, wherefore display devices can be provided which have thinfilms of uniform thickness, and wherewith a liquid thin film materialcan be prevented from overflowing the banks. Thus image displays can bemade wherein there are no irregularities in brightness or color, and thereliability of those display devices can be enhanced.

If the liquid thin film material filling is done with an ink jetprocess, moreover, thin film layers can be selectively deployed inaccord with color differences, thereby affording the benefit ofimplementing patterning with fewer process steps than photolithographicmethods and the like.

The inventions described in claims 49 to 74 are next described in eighthto 11th embodiments, making reference to the drawings.

(8) Eighth Embodiment

A surface modification method relating to a first aspect of [this]embodiment of the present invention is now described using the drawings.

In FIG. 22 are plotted changes in angles of contact on a polyimide filmsurface and on a water-based ink (having a surface tension of 30 mN/m)ITO substrate surface, in a case where plasma treatments are conductedconsecutively using an oxygen plasma and CF₄ plasma. For themeasurements here, the surfaces of substrates whereon a polyimide andITO were formed, over the entire surface, where subjected to the plasmatreatments described earlier, and angles of contact were measured forthe ink noted below.

The ink used for the substrates whereon polyimide films and ITO wereformed was made by adding methanol, glycerin, and ethoxy ethanol to awater dispersion of a hole injection material (a polyethylenedioxythiophene to which a polystyrene sulfonic acid had been added).

The oxygen plasma treatment was conducted under conditions of an oxygengas flow volume of 500 SCCM, a power of 1.0 W/cm², and a pressure of 1torr, while the CF₄ plasma treatment was conducted under conditions of aCH₄ gas flow volume of 900 SCCM, a power of 1.0 W/cm², and a pressure of1 torr.

In the untreated stage, the ITO surface and polyimide surface actuallyexhibit water repellency, but both are made hydrophilic in the oxygenplasma treatment. It is known that, in a CF₄ plasma treatment, thehydrophilic property of an ITO surface is maintained as it is, while apolyimide surface is made water-repellent. When a glass substrate wassubjected to the same treatments, it exhibited angles of contact of 20to 30 degrees after CF₄ plasma treatment.

With respect to organic solvent systems such as xylenes, etc., whichgenerally have low surface tensions, when the same consecutive plasmatreatments were performed, ITO surfaces exhibited an angle of contact of10 degrees therefor and polyimide surfaces exhibited an angle of contactof 50 degrees therefor.

Polyimide film surfaces processed by the plasma treatments noted abovewere subjected to ESCA analysis. The results are given below in Table 2.

Table 2 [cf. orig.]

Key:

UNPROCESSED

O₂ PLASMA

CF₄ PLASMA

As is evident from Table 2, the oxygen plasma treatment results in anincrease in oxygen atoms, while the CF₄ plasma treatment results in adramatic increase in the quantity of fluorine atoms and fluoridation.The bonding modes showed that —COOH and —COH were initially formed inthe oxygen plasma treatment, and that Teflonization (—CF₂—) was inducedby the CF₄ plasma treatment.

The Teflonization resulting from the plasma treatments noted above isalso confirmed for cases wherein a negative resist comprising an acrylicskeleton was used. [These treatments] are thus very effective inmodifying the surfaces of organic substances wherewith pattern formationis possible by photolithography.

It was possible to obtain similar results also in cases whereconsecutive plasma treatments were performed under atmospheric pressure,power of 300 W, and electrode-substrate distance of 1 mm, with theoxygen gas plasma conditions being an oxygen gas flow volume of 80 ccm,a helium gas flow volume of 10 liters/min, and a transporting speed of10 mm/s, and the CF₄ plasma conditions being a CF₄ gas flow volume of100 ccm, a helium gas flow volume of 10 liters/min, and a transportingspeed of 5 mm/s. It is very effective to use atmospheric-pressure plasmabecause the time required to create a vacuum in the process chamber canbe saved and the same surface modification can be effected more simply.

When a fluorine-based gas plasma treatment is performed, although CF₄was used in the case described above, this does not pose a limitation,and other fluorine-based gasses such as NF₃ and SF₆, for example, can beused.

It is possible to control the wettability (surface energy) not only bythe process time, but also by such parameters as the gas flow volume,power, and electrode-substrate distance, etc.

Thus it is possible with the same consecutive oxygen-CF₄ plasmaprocessing to perform surface modification so as to effect liquidaffinity in an inorganic substance surface and liquid repellency in anorganic substance surface.

(9) Ninth Embodiment

A thin film formation method and a manufacturing method for organic ELelements comprising organic semiconductor thin films relating to a ninthembodiment of the present invention are now described, making referenceto the drawings.

FIG. 23A-23E are process cross-sections representing a method ofmanufacturing organic EL elements.

In the process diagrammed in FIG. 23A, banks 302 made of a polyimide areformed by photolithography on an ITO substrate 301. The pattern may be astriped pattern or a pattern wherein circular shapes are removed. Thematerial forming the banks is not limited to a polyimide, and anyorganic material capable of patterning by photolithography can be used.

In the process diagrammed in FIG. 23B, an oxygen plasma treatment isperformed for 1 minute with an oxygen gas flow volume of 500 SCCM, powerof 1.0 W/cm², and pressure of 1 torr as conditions. Atmospheric-pressureplasma treatment can also be performed with a power of 300 W,electrode-substrate distance of 1 mm, oxygen gas flow volume of 80 ccm,helium gas flow volume of 100 liters/min, and transporting speed of 10mm/s. In the oxygen plasma treatment a hydrophilic ITO surface 3 and apolyimide layer 304 that is activated (made hydrophilic) are formed. Theoxygen plasma treatment exhibits effectiveness in ashing polyimideresidue on the ITO.

Following thereupon, in the process diagrammed in FIG. 23C, CF₄ plasmatreatment is conducted for 30 minutes with a CF₄ gas flow volume of 900SCCM, a power of 1.0 W/cm², and a pressure of 1 torr.Atmospheric-pressure plasma treatment may also be performed underconditions of an electrode-substrate distance of 1 mm, CF₄ gas flowvolume of 100 ccm, helium gas flow volume of 10 liter/min, andtransporting speed of 5 mm/s. The polyimide surface can be modified to aTeflon-treated liquid-repellent surface 305 while maintaining thehydrophilic ITO surface 303.

When the contamination on the substrate surface is of a mild degree,similar effectiveness can be obtained, without conducting the oxygenplasma treatment, by performing the CF₄ plasma treatment for 30 to 60minutes under conditions of a CF gas flow volume of 900 SCCM, power of1.0 W/cm², and pressure of 1 torr.

In the process diagrammed in FIG. 23D, a hole injection layer 306 isformed by spin coating. By adjusting the surface tension of the holeinjection layer material liquid, the hole injection layer material canbe patterned exclusively inside the ITO pixels. The spin-coatingsolution used was a water dispersion of polyethylene dioxythiophene andpolystyrene sulfonic acid diluted with ethoxy ethanol and methanol(totaling 75 percent) and adjusted to a surface tension of 30 dyne/cm.For the hole injection layer material liquid, the plasma-treated ITOsurfaces exhibit an angle of contact of 10 degrees or less, and aretherefore evenly coated. At the plasma-treated polyimide surface,moreover, an angle of contact of 60 degrees or greater is exhibited,wherefore the banks are not coated, and no cross-talk is induced. A holeinjection layer material ink may also be formed as a patterned filminside the ITO pixels by an ink jet process. The method of the ink jetprocess can yield significant savings in material.

In FIG. 23E, light-emitting layers are formed in three colors, R, G, andB, by discharging a red light emitting layer material ink 307, a greenlight emitting layer material ink 308, and a blue light emitting layermaterial ink 309 into respectively prescribed pixels from an ink jethead 310. The ink used for the green light emitting layer material wasmade by diluting a PPV precursor liquid with a mixture liquid of DMF,glycerin, and diethylene glycol. The ink used for the red light emittinglayer material was made by adding red pigment rhodamine 101 to the greenink made with PPV, in a ratio of 1.5 wt % relative to the PPV. The inkused for the blue light emitting layer material was an ink made bydissolving a polydioctyl sulfluorine in xylene. The angles of contact ofthe light emitting material layer inks 307, 308, and 309 on theplasma-treated polyimide surfaces are 60 degrees or greater, whereforesuperfine patterning is possible with no color mixing. When formingmonochrome organic EL elements, the light emitting layer can be formedby spin coating.

By employing the plasma treatments described above, a substrate may alsobe used whereon banks are formed in two layers, employing a glass layerfor the lower layer so that the angle of contact with the hole injectionlayer material liquid or light emitting layer ink is within a range of20 to 30 degrees. It is possible to avoid the danger of shorting at thebank skirts.

(10) Tenth Embodiment

A thin film formation method and a manufacturing method for colorfilters comprising colored thin films relating to a tenth embodiment ofthe present invention are now described, making reference to thedrawings.

FIG. 24A-24D are process cross-sections representing a color filtermanufacturing method.

In the process diagrammed in FIG. 24A, a resin BM (black matrix) 312 isformed by photolithography on a glass substrate 311. The pattern may bea striped pattern or a pattern wherein circular shapes are removed.

In the process diagrammed in FIG. 24B, an oxygen plasma treatment isperformed for 1 minute with an oxygen gas flow volume of 500 SCCM, powerof 1.0 W/cm², and pressure of 1 torr as conditions. Atmospheric-pressureplasma treatment can also be performed with a power of 300 W,electrode-substrate distance of 1 mm, oxygen gas flow volume of 80 ccm,helium gas flow volume of 100 liters/min, and transporting speed of 10mm/s. In the oxygen plasma treatment a hydrophilic glass surface 13 anda resin BM layer 314 that is activated (made hydrophilic) are formed.The oxygen plasma treatment exhibits effectiveness in ashing resinresidue on the glass.

Following thereupon, in the process diagrammed in FIG. 23C, CF₄ plasmatreatment is conducted for 30 minutes with a CF₄ gas flow volume of 900SCCM, a power of 1.0 W/cm², and a pressure of 1 torr.Atmospheric-pressure plasma treatment may also be performed underconditions of an electrode-substrate distance of 1 mm, CF₄ gas flowvolume of 100 ccm, helium gas flow volume of 10 liter/min, andtransporting speed of 5 mm/s. The resin BM surface can be modified to aTeflon-treated ink-repellent surface 315 while maintaining thehydrophilic glass surface 313.

When the contamination on the substrate surface is of a mild degree,similar effectiveness can be obtained, without conducting the oxygenplasma treatment, by performing the CF₄ plasma treatment for 30 to 60minutes under conditions of a CF₄ gas flow volume of 900 SCCM, power of1.0 W/cm², and pressure of 1 torr.

In the process diagrammed in FIG. 24D, a filter layer is formed in threecolors, R, G, and B, by discharging a red light transmitting pigment ink316, a green light transmitting pigment ink 317, and a blue lighttransmitting pigment ink 318 in respectively prescribed pixels from anink jet head 319. The angles of contact of the pigment inks 317, 318,and 319 on the plasma-treated resin BM surface are 60 degrees orgreater, wherefore superfine patterning is possible with no colormixing.

By employing the plasma treatments described above, a substrate may alsobe used whereon banks are formed in two layers, employing a material forthe lower layer wherewith the angle of contact with the pigment ink iswithin a range of 20 to 50 degrees. It is possible to avoid the dangerof color loss and film thickness irregularities.

(11) 11th Embodiment

A surface modification method and thin film formation method relating toan 11th embodiment of the present invention are now described, makingreference to the drawings.

FIG. 25A-25D diagram the benefits of forming banks in two layers, namelyof an inorganic substance and of an organic substance.

In the process diagrammed in FIG. 25A, laminated banks comprising aglass lower layer 321 and a polyimide upper layer 322 are formed byphotolithography on an ITO substrate 20.

In the process diagrammed in FIG. 25B, the oxygen plasma and fluorineplasma treatments indicated in the eighth to tenth embodiments areconducted successively. The ITO substrate layer and the lower bank layerglass surface are made hydrophilic, while the upper bank layer polyimideis made liquid-repellent.

In the process diagrammed in FIG. 25C, liquid thin film materials havingdifferent characteristics are coated in adjacent depressions bydischarging a thin film material ink A 327 and a thin film material inkB 328 from an ink jet head 326. After the plasma treatment, the anglesof contact indicated for the thin film material ink are 20 degrees orless at the ITO surface 323, 30 to 40 degrees in the lower bank layerglass surface 324, and 90 degrees in the upper bank layer polyimidesurface 325.

After baking, as diagrammed in FIG. 25D, the thin films A 329 and B 330are obtained. The plasma-treated polyimide surface 325 exhibits strongink repellency, wherefore, a flat film is sometimes not formed aboutperiphery of the bank skirts that are formed of polyimide. However, theITO surface 323 and the glass surface 324 both exhibit ink affinity,wherefore film formation also occurs about the periphery of the lowerbank skirts formed of glass and a flat film is formed on the ITOsurface. In the case of an element structured with an organic thin filmsandwiched between ITO and an electrode, as in an organic EL element, itis possible to prevent shorts from occurring because no film is formedon the ITO. In the manufacture of color filters, moreover, this is veryeffective in preventing the color irregularities caused by filmthickness irregularities.

As based on the eighth to 11th embodiments, as described in theforegoing, after subjecting a substrate having banks formed of anorganic substance on the same substrate to an oxygen gas plasmatreatment, that substrate is immediately subjected to a fluorine-basedgas plasma treatment, thereby imparting semi-permanent liquid repellencyto the banks while maintaining the liquid affinity of the substratesurface.

By using the methods described in the foregoing, furthermore, patternswherein the surface energy is controlled can be formed by a simplemethod on the same substrate, whereupon it becomes possible to formfinely patterned films with liquid thin film materials, not only usingconventional coating methods such as spin coating, but also using acoating method based on an ink jet process. That being so, it becomespossible to manufacture color filters and full-color organic EL deviceswithout color mixing, color irregularity, or cross-talk, simply and atlow cost.

1. A thin film patterning substrate, used for forming thin films inpatterns by a dip process or spin-coating process, comprising: a surfaceon which are formed banks and areas to be coated, partitioned by saidbanks, said banks including surfaces formed of an organic substance, andsaid areas to be coated formed of an inorganic substance.
 2. A thin filmpatterning substrate, used for forming thin films in patterns by a dipprocess or spin-coating process, comprising: a surface on which areformed banks and areas to be coated, partitioned by said banks, saidbanks including upper surfaces and side surfaces formed of an organicsubstance, and said areas to be coated formed of an inorganic substance.3. A thin film patterning substrate, used for forming thin films inpatterns by a dip process or spin-coating process, comprising: a surfaceon which banks and areas to be coated are formed, partitioned by saidbanks; said banks being formed in two layers including a lower-layerinorganic substance and an upper-layer organic substance, and said areasto be coated being formed of an inorganic substance.
 4. The thin filmpatterning substrate according to claim 3, wherein said banks includeside surfaces of a lower layer which are not covered by said organicsubstance.
 5. The thin film patterning substrate according to claim 1,wherein the thin film patterning substrate is treated by a surfacetreatment such that an angle of contact of the organic substance surfaceforming said banks is 50° or greater, an angle of contact with theinorganic substance forming said banks is 20° to 50°, and an angle ofcontact of surfaces of said areas to be coated with said thin filmliquid material is 30° or less.
 6. The thin film patterning substrateaccording to claim 5, said surface treatment being effected by plasmatreatment.